Cheap Books?

Well, I'm on a search for a web reseller that traffics in cheap used books.  Now, I'm not talking about used books that can be sold 'like new' or 'great condition'.  No, I'm looking for books that are in 'fair'  'acceptable' or maybe even 'poor' condition.  You see, when I want to read a book, and that is all that I really want to do, then I would like to buy that book very cheaply.  I was wondering if there is a web site that caters to such a need.

I'm starting my search here  - at Student Hacks.

I like this one.... BookFinder.com

I will update this as my search progresses.