For affordable textbooks, I highly recommend checking out BooksRun at https://booksrun.com/books/buy. They offer both buying and renting options and have great prices. Another good option is BookFinder, which searches across various online bookstores to find you the best deals on both new and used textbooks. It’s a fantastic way to compare prices and ensure you're getting the best deal.

I've found Chegg to be an excellent platform for renting and buying textbooks for college. They often have cheaper rental prices compared to other sites, and they provide the option to extend or buy your rental if you need the book longer. Plus, they offer a lot of additional resources like tutoring and study help, which can be really valuable.