Great site for used books

[limblips]

Alibris: Used Books, Used Textbooks, Rare & Out-of-Print Books

 

[morningbell]

Alibris: Used Books, Used Textbooks, Rare & Out-of-Print Books

I used to work at Harvest Booksearch and we used Alibis, we also used Global Book Mart.... etc... Alibris is good

 

[Bookbum]

Book searches

Alibris is good. You might also consider trying Bookfinder.

Bookfinder search dozens of sites for you (i.e. Amazon, Alibris, ABEBooks, TomFolio, Biblio, etc.) and displays them all.