Well, I found what I presume is a reliable window into the nature of texbook pricing.... Namely the US Department of Education.
http://www2.ed.gov/about/bdscomm/lis...xtbkstudy.html
I haven't gone over all the materials yet, so I'll reserve comment. For the moment.
On a side note, it is worth considering that this issue runs the risk of a "penny wise, pound foolish" mentality. For example, if your books cost $500 for the Fall semester, and $600 in the Spring semester, you'd notice immediately and react. If your tuition went from $9,826 for Fall to $9,926 -- or, if the cost of textbooks were included in your tuition -- you might not even notice, despite the fact you are out of pocket by the same amount. (Numerous studies indicate this kind of behavior is typical, btw.)