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)