I have heard there are ways for me to sell my textbooks, however I do not remember how much each costs.
Are there places where I could go to learn about their cost? How much should I price them?

The best place to look for the original price is of course the Mac campus bookstore website. Try pricing your textbooks based on how much you've used it and its condition. For example if the book is hardly used then you can price it as close to the original price but of course lower than the original price.