Textbook Rental on Amazon Kindle

I just saw on Fox Business that you can now rent textbooks on the Kindle. I went over to Amazon to check it out and read this:

Kindle Textbook Rental is a flexible and affordable way to read textbooks. You can rent for the minimum length, typically 30 days, and save up to 80% off the print list price. If you find you need your textbook longer, you can extend your rental by as little as 1 day as many times as you want and just pay for the added days.

Given the price of textbooks these days, this seems to be a great idea. Where was this when I was in college?