From an article written by Pamela Fiori for the Wall Street Journal, published 1/5/13:
Key Points: How to Shop for a Piano
1. Purchasing a piano is like buying a car. Figure out if you want a used or new one, what size you have room for and what you want to spend.
2. Don't go to a showroom by yourself. Bring your teacher, your tuner or a technician along to judge all the things you are clueless about.
3. Don't buy a piano online unless you have the opportunity to see and play it beforehand.
4. Make sure you get a warranty (for lifetime parts and 10 years' labor for the original owner; the warranty cannot be transferred).
5. Don't be surprised—or devastated—if you end up with a piano that's bigger and more expensive than you counted on. You really do get what you pay for.
6. If you want to know more than you need to about buying and owning a piano, order the fourth edition of "The Piano Book" (Brookside Press) by Larry Fine, with a lovely intro by Keith Jarrett.
Read the full article here.