According to Inside Higher Ed, some university presses are renting textbooks as ebooks.
For example, instead of buying a paperback or e-book for $20 at the Stanford University Press website, students and scholars can pay $5 to access an e-book for 14 days, or $10 for 60 days.
Stanford is not alone. Academic presses at several other universities are running similar rental programs, including the presses at the University of Chicago, the University of Iowa, the University of Michigan, and Ohio University.
Link to original article at Inside Higher Ed
Link to referring article: Academic Presses push ebook rentals to spur interest in the format
Link to PassiveVoiceBlg where I learnt of this article.