A piano is a big investment and you should research it thoroughly before you make a purchase.
I used the following book to help me purchase the studio piano.
"The Piano Book" by Larry Fine. It's updated annually, so be sure you read the annual supplement for the most current information. I have an older copy of the book that you may borrow.
Here are some useful links:
http://www.bluebookofpianos.com/ - Compiles new and used piano prices
www.pianoeducation.org/pnobuyng.html - Information about types of pianos and a buying guide
www.pianonet.com - National Piano Foundation
www.ptg.org/resources-pianoowners.php - Piano Technicians Guild