Don't buy any books before you start class. Most people in med school don't really need textbooks. After attending lectures/labs, and reading the syllabi, there isn't enough time to read textbooks (unless you are willing to give up your entire social life). Some board review books come in handy, but I would wait until the actual class to see if you need one. Someone told me the same thing before I started med school, and I was really weary because I had always been a textbook learner in undergrad. It's a good thing I listened, because I saved hundreds of dollars. The only book I think is absolutely necessary for everyone in med school is an anatomy atlas (Netter's is most people's favorite). You can usually get one for free by joining AMSA.