What should you buy? Understand that I am not  writing for people who are buying a barometer as an investment.  Buy something you like; something that begs you to take it home and that will suit your house.  A lot of people will want a barometer bearing the signature of their home town or somewhere nearby. Below you'll find a link to the Webster Signature Database, and a search by location will at least tell you if there is likely to be such a  barometer. It won't tell you where to find one, but you'll know if  it might be worth searching and waiting.  The database isn't foolproof, but it helps. Searching images online, using the term 'barometer'  and the name of the town,  will pull up barometers for sale - but it will also tell you the ones you missed when they were sold by dealers (who often show their sold archive) or auction houses.

 Buy the best quality you can afford, and read on re the costs of restoring, 
 
Look at online websites of specialist dealers to get a real feel for what is out there and what they cost. Browse auction catalogues and vist the better quality antique fairs, such as Antiques for Everyone, at the NEC,  or the Harrogate Antiques Fair at...Harrogate. Even if the stock may be as far above your touch as it is above mine, it will show you - if you don't already know -  what a fine stick or wheel barometer from a particular decade looks like. Yes, it will leave you full of lust and envy, but so will an afternoon's window-shopping at John Lewis. Acquire a copy of one of Edwin Banfield's books. Antique Barometers - An Illustrated Survey is a good starting point, unless you have already made up your mind between stick, wheel or barograph. See below for more details of these books.
The price for a working antique  barometer starts at around  £200 . Note that I wrote 'working' . A car can work but look rather tatty.   Unless you have won the lottery,  forget about 17^th and most 18^th century barometers. Christies sold a Queen Ann period specimen  by Daniel Quare for £20,000 ex-commission and VAT on the commission. But even early 19th century (Regency) barometers can be affordable. I've recently seen a  Sheraton, in fully restored/display condition, for £495. Later barometers are likely to be cheaper.
At the moment prices seem to be depressed. Good news for buyers.

A high-quality barometer in wonderful  and original condition and signed by a well known maker will be expensive. You hear antiques experts on TV extolling the glories of Georgian furniture that has passed down one family and acquired a glorious patina. Many barometers are restored, and some have had bits replaced, often tubes and bits of pediments or stringing. That's not unexpected -  we all need a bit of help as we get older.  It's just good to be told,   or to recognise for  yourself,  what's been done, because then the barometer is honest, even if, from an investment perspective, the value may have been reduced. But when the restoration equivalents of the face-lift, liposuction,  Botox, Grecian 2000 etc become excessive, the barometer loses authenticity, though it may still be an attractive object.   Beware of  barometers made up from  miscellaneous components taken from scrapped barometers and with a dial or level plate that bears the name of a maker who never saw any of the other bits and would not have liked them if he had!

It goes without saying that all sorts of quality issues will be reflected in the price. Why is one 1810-period barometer several times the price of another?  The type of veneer and the quantity and quality of decoration affect the price. Outline stringing (simple,  or rope/chequered etc), line inlay, crossbanding, paterae (especially unusual motifs) etc will all increase desirability, though some veneers, such as flame mahogany, can stand on their own feet without elaborate decoration. The shape of the case and, in the case of wheel barometers, the diameter of the dial are important. Good engraving is worth looking out for as it really heightens the appeal. The name of the maker is also a factor. English names may be more expensive, though the funny thing is that some barometers with English-sounding names were made by  Italians whose names have been anglicised. Francis Molton of Norwich is a good example.  Unusual barometers have a rarity value that increases the price. It's often just enough to look at a barometer and simply know you are looking at something special.

Beware of anonymous barometers, especially in that Sheraton style, because they may be Victorian or later copies – not fakes, just  repro – and they tend not to be signed. They have different engraving etc: much larger, darker engraving of the weather indications,  and heavy engraving around the centre of the dial.  This is fine if they are appropriately priced, of course. 
However, there are unsigned  early 19th century exceptions out there that would grace any home. You just have to do the homework, which is where Banfield's books are so good. No, not good - they are indespensible.  


Caveat Emptor...

Where to buy?

The choice is between the reputable specialist, the local antique shops, or the antique auction.


Auction

You may pay less than if you buy from a dealer, only provided you know what you are doing.  Remember   the following:

• Buyer's Premium  adds around 20% to the hammer price, depending on the auction house policy. That's £20 for every £100. And VAT is levied on that premium.  A £300 barometer could cost you about £375  
• The auction house is  not allowed to post a barometer with mercury in the tube - you have to collect it or arrange specialist collection. Transportation is not straightforward and if not done properly can smash the tube, leaving you with a car covered in glass and mercury. (The movement of the car can cause the mercury to rise and fall so violently that, if it rises quickly it can smash through the top of the tube. You can get a specialist to plug the tube which makes it transportable -  but still not postable.   If  done badly, plugging can push air into the tube, which is very  bad news, and, even if it doesn't,  when you get the barometer home,  you have to set  it up. 
•  A 400-mile round trip by car will add serious ££ to the cost. That £375 can be pushing £440 by the time you take it out of the car after having filled the petrol tank and stopped for a coffee or two.
• If the barometer is in perfect working order and attractive enough to hang straight on the wall you may be lucky. Just do serious homework before you start bidding, and know when to sit on your hands. It may not be as easy as you think, unless you have the temperament of Yoda from Star Wars. One very experienced barometer dealer told me that he once bid on the wrong lot and ended up buying a doll with one arm.... Go to some house clearences first and buy a cheap trinket or pot that you can donate to the charity shop, just so you get the feel for bidding.
•  It is infinitely better to see the instrument  for yourself than to bid from a picture in a catalogue. Believe me: I have been to view barometers on viewing day having first seen them in the online catalogue - and some have looked terrible. I am not accusing the auction houses of photoshopping the images; it's just that when you set up lighting for photography you bring up a shine on the veneer that gives a richness to the wood that may not be there. You don't want to overspend  if you are bidding online or by phone, because your winning bid may be followed by an unexpectedly high restoration bill. So do look at the barometer on viewing or sale day. And if you are disappointed, don't buy it. Better to have wasted the petrol than the cost of the instrument. 
• If it requires restoration beyond, say, rethreading the weights, you ought to think of circa £300 restoration costs, and be aware that it could be  more depending on the amount of work that is necessary and the rate charged by the restorer.  If you are prepared for £300 you'll get a pleasant surprise if it's less,  and you shouldn't get a heart attack if it's more. Remember it’s a highly skilled, labour intensive task.  Most auction houses will send you hi-res images and a condition report, and some will let you take your own pictures. If you can get images of the front, back, sides, tube, each dial etc, and especially of any obvious damage – you can send them to a restorer and get at least a ball-park figure before you waste time going to the auction. Then compare it with the cost of a similar instrument from a specialist dealer. If you take a chance, and that £440 barometer is going to cost a further £400+ to clean the case, replace some missing bits, resilver the dials, and refill or replace the mercury tube, you've spent over £800 at least. What is the barometer actually worth? Would you have had to pay £800 in a dealer's showroom for it? Of course, if it bears the name of one of your ancestors, you may be more than happy to pay over the odds. If you find a good stick barometer with curved glass that's cracked, beware. The replacement glass will have to be handmade for your restorer. Ouch, as they say. That's not to say that the barometer won't repay restoration, just to warn you.

• Ebay
   In my humble opinion it's not a good place for the novice as many of the sellers either do not have a clue or else try to get away with asking high starting or BIN prices for inferior instruments that you probably won't have the chance to see first and would get more cheaply in a conventional auction.  I recently saw a very tatty specimen  - one  that might have been good for demonstrating the construction and working of a barometer  - but although it  appeared to have mercury in the back, the dealer was offering to post it for £12. I did contact the seller, and received the answer that  it had some silvery liquid in the tube but he didn't know what it was...Imagine receiving that package...  You see onion tops described as rare Regency instruments; 1810 sticks described as early 18th century; tatty 5-glass instruments catalogued as early 19th century.  Ebay is crammed with undesirable, if not hideous, barometers,  Out of 2,600 lots I flicked through  recently, there were no more than about 10 mercury barometers and among those was just one attractive Sheraton and a very desireable Francis Molton (the latter was being sold by an  antique dealer who also had a shop where the barometer could be viewed)
  General Antique shops
• This term covers a very wide spectrum of business, from  (in Britain)  LAPADA or BADA members down to  what can look rather like junk shops.
•  Some may sell only one or two  undistinguished instruments needing restoration, and the staff may know nothing about barometers at all. Do your homework.See above, under auctions. 
• Some will stock a few barometers, often to complement their furniture showroom, and have a specialist restorer who repairs/restores them, and who will deliver your purchase and set it up for you. As you may not know this, do your homework and ask questions.
• You may get a gem, especially a local name. 

Specialist dealers

• Some only stock the upper end of price and quality; others offer a good range of periods and prices to suit all tastes and pockets.
• You will get good advice. Good barometer dealers are passionate about their stock.
• The instrument will come fully restored, working, and with a guarantee. You may well even get images of the instrument being restored - assuming it needed restoring.
• Many dealers will bring the barometer to your house and set it up for you, especially if you don’t live too far away. This may be an extra cost to you  or an integral/negotiable part of the selling price.
• You will pay a premium, but know exactly what you are getting. A reputable dealer  (if you're not sure, look for members of an association such as LAPADA, the  London and Provincial Antique Dealers' Association), or BADA (British Antique Dealers Association) will not take advantage of a buyer's inexperience to pass off a common 1850s onion top  as a rare George III specimen. Those who repair clocks as well as barometers may be members of the British  Horological Institute. I've put a list of  reputable UK specialists below, but there are undoubtedly many others, and I would be very happy to include them on the site..