Pharyngula complains that textbooks are too expensive. He thinks publishers should stop coming out with so many new editions. I doubt this helps. As students know more about new editions, they are willing to pay less for existing books. "But they have to buy! It's a monopoly!" you say. Well, there's little evidence that adding bookstores to an area reduces the price of books.* You might consider instead online bookstores, which typically sell books at a 5% discount to the on-campus store. According to this article by two economists at Delaware, however, the websites with the cheapest prices have the least availability.

I don't think, either, that the marketing design of graphics in texts is driving price. That's a fixed cost, not variable. Moreover, the decision of which book to buy isn't the students' but the professors'. If professors are choosing books because the illustrations are sexy, why blame the publishers??

*See John Siegfried and Christopher Latta, "Competition in the Retail College Textbook Market,: 17 Econ Ed. Rev. 105 (1998). Available from ScienceDirect with subscription.