Buy Cheap Textbooks
Unless you are getting textbooks for free, you might have noticed that you college bookstore sells their textbooks at the highest price possible. I think that's how they earn funds for college projects. So therefore, if you are into helping your college financially, please keep buying your textbooks from them.
Otherwise, try to do some research on the internet about the online book sellers. You will find the same textbook your college bookstore sells for 100 bucks at half or lesser price. Yeah that's crazy; I was completely shocked when I done the research about textbooks out of desperation. Since then, my motto has been "Never Buy Textbooks from College Bookstore." I used to think that the books would be cheaper in my college since they can books in bulk and sell to us the students. But, as I learned, that's not the case.
You can start with eBay. EBay is a website where people sell and buy; buyers bid on items and the buyer who bids the highest price will be able to purchase them. Almost everytime, you end up buying items at the cheaper price than their market price. You can bid on both new and old books.
Buy.com is another auction website that is very similar to eBay. The only difference is that eBay is more popular and thus have more users, which means more variety and number of items. Other popular source to buy cheap textbooks is to visit Amazon.com. Barnes and Nobles website offer books at quite a good price too.