So, you've found a piano on Craigslist or Facebook marked as "free" and that seems like a pretty good deal. Or you have budgeted some money for a reasonably priced instrument and you head to the seller to make an offer. Conventional wisdom says you should invite your friendly, neighborhood piano technician along! Some provide this service free of charge and some charge a nominal rate. But do you really, really need someone to tell you that free piano is a good deal? Or that baby grand you've had your eye on is so pretty and it's only $400! You don't need someone else to confirm to you that you should jump at the opportunity, right?
Stop right there! Whenever those thoughts of piano justification come into your head, that should be a signal to you! Please, please, please call a piano tech to come with you! They can tell you all sorts of things about the piano that you wouldn't have noticed or thought of! They'll look under the lid, take a gander at the sound board, work the action and note what's good and what's wrong! Maybe the key tops need to be replaced. Your tech can tell you approximately how much that costs. Perhaps the action badly needs a regulation so that it can actually be played. A tuner/tech can tell you what all is involved and how to get the best regulation for that piano.
A technician friend of mine had a customer who teaches piano. She has always wanted a vintage baby grand for herself and for the lessons she'll teach. Finally she found one and jumped at the chance to own it for a very reasonable price. She spent her savings and had it delivered. Like any wonderful piano owner, she knew she'd need it tuned soon after its move and called in my friend. She was surprised and disheartened to learn that it needed quite a bit of regulation work, the mover had been rough and broken parts of the pedal box and once the regulation work was done he had to grind down some of the plate so that action could work properly. She ended up spending more on the work than she did on the piano. Had the teacher consulted him before hand, he couldn't have told her about the rough mover (but he could have pointed her to a qualified piano mover!) yet he could have seen from even a cursory inspection that the plate was going to be an issue and the action would require a lot of man hours to make acceptable. Now, that's not to say that she wouldn't have or shouldn't have purchased the piano. Perhaps she would have gone forward, but she would have gone forward with knowledge and information to make a decision that was costly.
Think about it this way: Would you purchase a used car without consulting your mechanic? Would you purchase a house without an inspection? Would you put in a pool without the expertise of a construction specialist?