This economics oriented podcast gives a pretty nuanced explanation of the rapid rise in textbook prices and various responses. Sadly, they do not mention the response that many of us are engaged in--the production of high quality, open-source, free textbooks. After listening to the podcast, I have a much better understanding of the variables that drive textbook prices. I highly recommend a listen.
You can hear the 15 minute piece here: http://www.npr.org/blogs/money/2014/10/03/353300404/episode-573-why-textbook-prices-keep-climbing