From Peter Klein at Organizations and Markets: Students: Consider Renting, not Buying, Your Books
"Chegg is the Netflix of college textbooks. Get your book in the mail, along with a prepaid return address label, don’t write in it too much, and send it back once the semester is over. I took a quick look and the savings appear to be substantial for brand-new books, modest otherwise (because there are robust secondary markets for used textbooks). The newest edition of a book I assigned last semester is $127 new from Amazon, $72 for a one-semester rental from Chegg."
HT Steve Leider