I always try Long's (now B&N down on the South Campus Gateway) bookstore for my books, supplies, etc. first. They always seem to have what I need in stock and at a pretty good price. They do have the textbook buy back, and they seem to be pretty fair when it comes to what they'll give you for your books (which is important to me!). Now that they've moved to the new South Campus gateway, they seem to have even more neat stuff and a beautiful new store!