My first semester at college I spent $700 on textbooks, some used and some new from the on-campus bookstore. My last semester at college I spent $300, some used and some new but I bought online and from private sellers. A savings of $400 per semester adds up to $3200 over the four years at college.
When I started trying to save money on books, I started by buying online at barnes and noble. Going to barnes and noble through upromise gave me three percent back on my purchases as well. This cut my costs down to $500 per semester and I thought I was doing well.
Then my last year rolled around and my DH and I started dating. He was even better than me at finding deals on textbooks. That year I checked half.com, amazon, textbooks.com, abebooks.com and campusbooks4less.com. Not one site had all my books for the best price but by checking them all I found all my books for cheap. If I had known about these sites at the beginning of college I would have been able to save more or work less.