My next option was the street vendors. Book street vendors line up on the road every beginning and end of the term. They offer to buy your books or sell you other used ones. BEWARE! These vendors can be JUST as expensive as the bookstore. They are just better at convincing otherwise.
So get off the streets and get on your laptop, because I'll let you in on my little textbook bargaining secret.
Here we go: I don't buy anything at all.
Renting textbooks is a surprisingly untapped resource. My $160 math textbook, I rented online for $30. My $120 chemistry textbook I rented for $34. I use www.book.ly to find the cheapest renting sites but I always end up using www.CampusBookRentals.com. CampusBookRentals has tons of coupons online I can use to keep more money in my pocket. Book.ly also provides you with more coupons too!
Honestly, if I bought all of these book, I would have at least $400 missing from my bank account. I would also have less space for my clothes!
If you are sick of spending all of your money on books, try renting. You'll be thankful soon.