this is the university bookstore (which is run by Barnes and Noble but I think this policy is separate from them.). I suppose I could have said to the students "you will have to buy your book online" but some of them might not have liked that. Some student athletes also get books paid for on their scholarship and probably are expected to buy from the university bookstore. Like I said, I am just a grad student so I just do what I'm told. I was teaching a summer course and they called and I just did what they said. If I was a tenured prof I might have took the time to figure out something else.

Regardless, in the courses I've taught that use textbooks I've always encouraged students to use older editions if I know that they are substantially similar to the latest edition.