... at the campus bookstore, then sell them back at the end of the semester, unless they're part of your major, then best to keep them. That's about it really, other than seeing if anyone else already has them. Lot's of times in your major you'll know people who took the course the previous semester or year and don't mind loaning you the book, pay it forward, etc. Borrowing it from someone else tends to be cheapest, if it's a regular elective class then tons of people have it lying around, if it's from a higher level class it's probably in your major and you should know someone from the year ahead who has it and won't mind lending it to you, or maybe selling it for cheaper than the used copy goes for. Hunting for deals online is likely to take just as much time as scoping out people you know who might have a copy.