From the UMP blog:
The University of Michigan Press announced today that it launched a new ebook rental program for more than 250 of its scholarly titles, allowing students or faculty to rent digital copies of the books at a discount for a month or six months.
Costs will range from 40% of list price for a 30-day rental to 75% of list price for a 180-day rental. For example, a paperback textbook might carry a list price of $22.95; it could be viewed as a rental for $10 for 30 days, or $18 for 180 days. Scholars who rent a book will have the option at the end of the rental period to buy it permanently at an additional charge. Purchased versions include additional interactive features.
If customers endorse the program, the Press may make as many as 325 books available by the end of the year. ...
To see a list of the titles currently available for rental, visit www.press.umich.edu/ebooks.
I never pay more that 75% to buy a paper copy; why would I pay that much to rent the ebook? It's a rip off.