Textbooks are expensive!
Especially if you go to buy them at the bookstore, we all know that you should buy used, but are there any other options out there? Always check your bookstore about 2 weeks before the semester starts to find out which books your professors will be using. If you wait to buy your books
after you get your syllabus it will usually take awhile to get them so you won't have your books for the first few weeks.
My favorite place is personally Amazon, because of their service and shipping times. You are able to find almost all books here, and can get older editions and used editions for pretty cheap. I also highly recommend Abebooks for getting rare and graduate level textbooks because they offer many international editions that are made outside of the US, and you can pick up these books for much cheaper than you can get at other sites or your book store.
Some bookstores have better buyback policies than others. If your University doesn't have a good buyback policy, I would recommend that you sell your textbooks using the services on Amazon. You are likely to get more money selling back on Amazon than you would otherwise, and if your University won't buy back your books than you should definitely look into using Amazon.
