It took me three years to realize that I didn't actually need textbooks. My senior year, I didn't buy a single book, just the course packs put together by my professors (if they had them).
The course packs were either all original material, or an original composition of parts of case studies, essays, and text books; they were almost always under $50 (except in the case where licensing the copied portions drove the cost higher).
If a professor is actually just teaching out of a standard text book, all the relevant information is taught in lecture. If there is an express need for a textbook, it's on reserve at the school library.
I would urge every student to only consider purchasing a textbook if they really think they need it two weeks into class. Textbooks are overpriced, only a small amount of the information is relevant to the class, and the information is often redundant and can be found in lectures/slides. (if the idea of coming to class without a book is scary, check your school book store's policy on returning books)
I (fortunately) realized this in first year when I, at the end of a semester had opened exactly one of the 4 textbooks, and then only read < 1 chapter.
The alternative to buying a copy of texts you really need (and I know there are a lot of legal issues with this) is "finding" the book online (and I haven't yet had a book I couldn't find trivially). A couple of PDF's instead of a pile of dead trees, and I have the added advantage of in-text search.
I got by with purchasing "international editions" from India on eBay, which had the same content in English, but with cheaper quality printing and no color. It was about $15 for a normally $150 book. Between that and downloading PDFs of other textbooks, I got through each semester with just around $50 of textbook budget.
Even if you don't need the textbooks, they might still be well worth it. For me, at least, they cost a small fraction fo the tuition. If you are paying $50K a year for your education, you need to maximize the value extracted. I got more from lectures when I had read the relevant chapters first.