You have to admit, textbook prices are pretty insane. Part of that is due to used book sales, part of it is due to new editions that get regularly released to counter used book sales, and part of it is all the useless extras that get bundled with many of them. Well, and part of it is that it's a relatively small market so they have to charge more to make money, and that with all the publisher consolidation there's little competition to control prices. Oh, and there's the fact that professors tend not to check the prices of textbooks when they select them for their courses. So, um, yeah, there are a few reasons why textbook prices are inflated.
Piracy isn't going to fix the problem, really, just bypass it for some students. The real fix would have to start with the faculty - students need to talk to them and get them to either pay more attention to pricing, or to look at textbooks distributed outside traditional publishing venues (like some creative commons textbooks that can be freely downloaded or printed cheaply - there aren't a lot, but there are indeed some like that being used at ivy league schools, written by professors, and that underwent peer review before release).