I am in graduate school for an MIS degree.
The cost of my textbooks is included in my tuition (nice! and super nice because my employer does not reimburse for textbooks separately).
However, more often than not my textbooks sit on the bookshelf. I end up using Google books in order to search for passages read them if there is a free preview or use the page numbers to find the passages I need to review in my physical book.
Being able to search on text is far more useful, in my experiences, than sticking with the dead tree. I had to change how I viewed ebooks because I was one of those who liked to write in my book, highlight etc. It is definitely not as nice to do in an ebook format.
I have purchased ebooks by searching them out on Google, the publisher's site. I have not typically used coursesmart due to the subscription model as often (although for classes I did not care about and knew I did not want a physical copy I did do just that).