To start I have to say that CampusBooks.com does not support the illegal distribution of any materials but since it is currently happening in the textbook industry I feel the need to address it as a way for students to access information. If not for the illegality, the idea makes perfect sense; a student buys a $150 book, copies all the pages and creates a PDF and then shares it with all their friends in class.
The concept of photocopying a book is nothing new. The internet just allows the old photocopy to be scanned and shared with more people in a faster manner. Years ago the big problem was students using university copy machines to make the copies! At the time, the problem was not so widespread, and as long as the University made their ten cents a page they turned a blind eye. As long as the university can still generate $20 for a 200 page textbook they didn't care so much. But converting those copies into a PDF file eliminates the need to pay for photocopies.
The prohibitive cost of photocopying a textbook that is a few hundred pages also kept the practice in check. For thinner books this will probably suit you fine because the costs are nominal. But if you are going to just print the book off so that you can read it you may want to give it some serious consideration as the overall cost could easily be more than simply buying that book online. And don't forget what you are doing is illegal and could have negative consequences.
Again, we have covered this in the past so I am just going to reference some old posts covering the topic.
by: Jeff Cohen