OER is a nice way to go, but I’ve also mentioned before how to restructure the textbook business so the economic balance is righted.

tl;dr: Professors aren’t doing the learning, so at most they should recommend one or more textbooks, but never require them. The students should choose their own textbooks or otherwise fend for themselves (many are already doing this anyway, so why disadvantage them further with the economic burdens) and direct market forces will very quickly fix the problem of run-away book prices.

Professors should not be middle-people in the purchase decisions of textbooks.