Bookman will buy your old books and give you credit or cash. THe credit can only be used towards used books (although sometimes there are nice people who realize you made a mistake and let you use credit for a new book anyway).
THe selection is huge and really pretty good. Particularly with the new books thrown in to fill in the gaps.
It's a little confusing because there are two sections of fiction...one for trade paperback (i think that's what they are called, the smaller, cheaper editions). the other section is for fancier editions.
go here with some time on your hands to look around.
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