Check to see if you can buy any of your books off some of the students a semester or two ahead of you in the program.
I never buy ANY book from the bookstore -- Amazon or Ebay always have way better options price-wise. Just be careful about renting textbooks -- my program has Med-Surg I, II, and III, and they all use the same textbook. If you rented that same book three times, you'd be better off buying it.
Used/older editions sometimes work just fine for some of your book needs, too -- you can get multiple careplan / nursing diagnosis books for under $5/each (including shipping) at places like BetterWorldBooks.com. Same for lab/diagnositic books and "clinical companion" books (the smaller one you can take to clinical instead of your textbook). Same for "optional" books and study guides. Same for drug guides (the difference between a 2011 drug guide and a 2013 will be minimal from an informational standpoint, but the price difference is about $30).
In addition to the assigned textbook, I personally like to get an entirely different textbook (like Med-Surg or Critical Care or Psych or whatever) from BWB so that I have something different to read -- sometimes the way a different author describes a disease process or a procedure will just "click" better for me versus how my required textbook author described it. A $5 textbook from another author can make all the difference when it comes to understanding the material, passing the class, and passing the NCLEX!
Another suggestion is to ask each instructor if the "required" books are actually required to pass their class (as in, will there be assignments that you will need that exact book in order to complete). My first Med-Surg class had a particular lab/diagnostic book listed as "required" and a particular study guide listed as "required" and a particular NCLEX Review book as "required"... turns out we didn't need ANY of those exact books... just needed "a" lab/diagnostics book, and that students in previous classes found the study guide helpful, and that studies show that students who do practice NCLEX questions do better than students who don't. So the instructor made the study guide and NCLEX books "required" as a way to "help" students. Saved myself close to $200 on books that were allegedly "required" just because I took the time to email the instructor before the semester started.
Ditto for my psych-nursing class -- we were supposed to get a "required" psychiatric nursing diagnosis/careplan book, but it turns out that the instructor just wanted us to have "a" psychiatric NANDA/careplan book, b/c our program's required book was crap for the psych portion of the program. Saved myself another $75+ on that by getting an old one from BWB (and my classmate borrowed MY book all the time b/c it was way better than the "required" one she had gotten!).
Welcome to the adventure that is Nursing School!