The high price of college text books has led to a thriving rental market reports the recent Washington Post article, "College students rent textbooks to save money." Instead of buying textbooks and selling them back at the end of the semester many students are simply renting the textbooks. It isn't surprising that the rental price is lower than the price of buying the book. It would be interesting, however, to see whether it is lower than the price of the book less the sell back price.