I can't believe there are people that selling their $120 BIO book back for $5 and next week we can see it on teh shelf the same one with his drawings and highlights in there for guess what? $90. So please, try this and you can trade too...spread it around campus so people you "don't know" have your book can trade you books that "you want."
I heard from a friend of mine he gave me the link after we chatted about how freaking EXPEN$IVE books are...and he said he saved a lot by trade books with people.
PS: I don't work for them or anything I just have sh#%loads of books that I never trade but want to but don't know where.