To be honest with you, I'd say that for some people none are required. All our class notes are given out in packets (except 1 sensory class), and contain all the information we are required to know. I haven't bought any books this year; I also never read the books. I just don't feel like there's enough time to study all my notes and read the textbooks. If you do feel inclined to read the books, they are all on reserve in the library and some students do find it helpful to buy certain anatomy or immunology books that they may need to reference. I would recommend you just see how the class goes and buy the books later if you truly feel like it would help. You can always buy them from the upperclassmen who DO buy books (people always end up spamming the listserv with old books they're getting rid of).
Short answer: probably no books are necessary (especially if you're living in the RC and can go to the library any time).