I used this in almost every class, and in anatomy it's pretty much necessary. Stedman's and Dorland's are the two most popular dictionaries. To save money, you can usually get a good deal on an old dictionary. I used a 1966 Stedman's and it worked out great. However, for quick reference, I found Webster's pocket dictionary to be remarkably useful, despite its vastly abridged vocabulary.
Some schools have book sales ahead of time.
However, I wouldn't buy new books ahead of time, except the above-mentioned Netter and a good medical dictionary. At our school, AMSA has a booksale at the beginning of the year with good deals. You may find that the recommended text is not very helpful, and that most people use a different text. Once I found out about this I started saving bigtime on book costs. Review books are great.