On eBay and Gumtree I often see pianos that are overpriced, but also see many that are a great deal. Keep in mind that many piano sellers don’t know the worth of what they’re selling, so if you’ve done some reading up on the subject you probably know more than they do. I’ve seen completely worn out, untunable pianos from the 1890s priced at £500 or more! They should be paying people to take them to the skip! Before forking out money for a second hand piano it is always a good idea to try it out for yourself and/or to call the piano tuner to evaluate it – I charge a £25 call out fee to inspect pianos in Leeds or Bradford.
A common problem in old pianos is tight and loose centre pins. To see if the piano has this issue, press the sustain pedal and gently play several notes. If keys are sluggish or sticky there may be trouble ahead – with 264 centre pins in a piano, it could require extensive regulation work to bring it up to standard. I recently spent an afternoon after a piano tuning in Leeds replacing centre pins in a used upright and while it can be done, the more notes that are sluggish or sticky, the more work will be needed.
If the piano sounds relatively in tune with itself but one or more notes sound badly out, that’s a worrying sign of loose tuning pins. Loose tuning pins aren’t always a problem in themselves (there are fixes), but if there are a lot of them it’s a sign that the piano has not aged well (and an indicator there will be other problems). Also look for rust around the tuning pins, excessive rust could cause you problems down the road with strings breaking. If there are several or more strings missing that’s an indicator that the piano won’t be able to be brought up to concert pitch.
Take the front panels off and check inside. Check it’s not been ravaged by mice and that the pedals are working properly. Check that there are no cracks on the soundboard (the wooden area behind the strings which is the main resonator of the sound), as wide cracks will cause buzzing and tuning stability problems. Check the bridges (the part of the piano that the strings run over) are in good condition and that are no cracks (cracked bridges will ensure that the piano is out of tune again right away and causes buzzes). These structural problems will mean major repairs which often aren’t worth it on a cheaper instrument.
If you find the serial number, there are books and websites for you to date the piano. Sometimes the date of production is written on the side of the bottom key. I would advise against buying anything made before 1950 unless it’s a particularly high quality instrument like a Steinway or a Bechstein that has had extensive restoration work (when buying a piano: the newer the better in the majority of cases).
You also need to use your ears and listen to the tone! Get an idea whether it’s an instrument you could fall in love with. If the piano is badly out of tune this will be harder as it’ll be difficult to hear past the horrible tuning. But if you get a feel for the instrument before its been moved, once its at your house and been worked on by the piano tuner, it will become one of your most cherished possessions.