I really hope someone, someday, can successfully cut the legs out from under the racket that is the textbook market. Forced bundles, superfluous editions that do little but change the page numbering, etc. I suspect a healthy enough used-textbook market could do this: As a teacher, if you know students can obtain an older edition easily, you could freeze the version of textbooks you use.

I don't know to what degree university politics would forbid using older versions, though.