Why do books cost so much?

I spent $500 on books my freshman year of college. Why? Because I was foolish and bought new books from the campus bookstore. Never again. I don’t think we should buy books at all. I think we should use free source materials, book rentals, and book sharing. Yes, sharing like iTunes, except iRead. Not every chapter matters. Some chapters matter more and we should be able to pay by the page.