It is difficult for a lot of people to buy books at the end of the semester, though. You don't know if they are going to change editions or change books completely, and you may not know what teh changes between the editions are, or to what extent the professor will use the material like the unit questions from the book, which can vary greatly between editions. I'm taking this human/computer interaction class and the difference between the second and third editions is like night and day. And I took an art class when I was at NVCC that seemed like everyone in the class had a different edition of the book and it didn't matter.