When I studied my engineering degree (not in the US) at a pretty high-ranked institution, textbooks were rarely used. I think I only actually purchased and used one, and it was approx $50 (brand new, used was cheaper). Often a course text was set, alongside the instruction of "don't bother to use it" (!) One prof did use his own book (the only time I saw this) for teaching, and had uploaded the book as PDF chapters (searchable text format, no less) to the online course page.

I therefore have a double-take when I read about people spending upwards of $1000 for books in a semester - I just can't imagine what that course would be like, or how students would feel with that kind of teaching that is presumably very heavily reliant on the book.