To those teaching and requiring your students to use a textbook: do you know what that textbook costs? Many do not, and thus tell students to buy a book without proper information. This is much like in the health industry, where physicians prescribe drugs without knowing their cost. No wonder publishers exploit students like pharmaceutical exploit their captive clientele.
Ted Bergstrom, who is already a driving force in reducing the cost of journals, now has teamed up with Maxim Massenkoff and Martin Osborne and created an informative website, PoET, that gives the information that publishers are reluctant to give faculty: the price of their textbooks. One can also leave a review of a textbook, and thus make the adoption of a textbook a more informed matter.
To be honest, I would prefer teaching without a textbook. But students nowadays require one and complain when I stray away from it. I tell them to buy the one that is the closest to what I teach. And I do not care which edition it is. Now I will also put the price in my optimization.