The problem is, my college gets its textbooks custom published for their own classes, and the technology ones change every year, sometimes every semester. Also, it's not just the book--it's the code that comes with it for downloading programs and access for the quizzes and labs. They are a one-time-use product. Sometimes the code is half the cost of the book.
I might have another student who will sell me his books (at discount) and then I can order the codes on line (for a fee). I have to check to see if the total comes out at a good price.
Yes, our libraries have a cooperative lending system, too. As a student, I also have access to the libraries of other local colleges.