I would agree with the other posters. When I took my "required" 1st year book list to the bookstore, I found that I was going to be staring at a $600-$800 investment. After getting some advice from my 2nd year "big sib", I purchased a total of TWO required texts, and a couple of board review type books. Obviously, things differ at different med schools, but as an example, the notes given to us in both biochem and physiology basically eliminated the need for ANY further reference (although I did use BRS physio to help with difficult concepts).
I realize that different personalities will take different approaches to this, and some people will simply not be able to sleep at night unless they have all the the texts, supplements and CD-ROMS which the curriculum requires. The fact is, practically all of the BIG textbooks contain about three times the information that will be imparted to you over the course of the year. While most of that extra information may be useful to an individual wishing to pursue a PhD in that particular field, it is simply overkill for a medical education.
Hope this helps!