Open Educational Resources (OER) include free textbooks and other material. They are written to the same standard as traditional textbooks but have a different distribution model. They are one way authors, libraries, and universities are trying to help reduce textbook prices.
If your class is using an open education textbook, your instructor will have provided a link to it in Canvas or your syllabus.
Otherwise, you might use OER textbooks to supplement your course readings, if you find the textbook confusing or just want another presentation. There are even entire OER classes, especially in the sciences, if you want a "peer reviewed" experience.
If you have any questions, feel free to reach out to any of the librarians at Plough Library.
Katie Gosa gives a presentation at TEDx U. Texas-Arlington on the Open Education movement.
There are other ways for students to save money on textbooks:
Course Reserves: Your professor may leave a copy of the textbooks"on reserve" with the library. These can be checked out for three hours but cannot leave the building. You are free to scan or photocopy the readings for your own use. If the instructor does not have a copy on course reserve, you can always ask them if it would be possible to do so.
Search the Library: The library does not typically buy copies of the big "Intro to Calculus"-type textbooks for the permanent collection. We do sometimes have copies of other books that might be assigned. You can search the library to see.
Sharing and Used Books: Outside the library, you might consider time-honored money-saving methods like sharing a book, shopping early for used books, etc.
Note from Alfred Wallace, Instruction Librarian:
As someone who has worked at a textbook store, library, and spent years as an instructor and student, I strongly recommend that you use the textbook and keep up with the readings if at all possible. Do make your money concerns known to your professors, but doing the readings and exercises should be key to succeeding in the class and learning material for upcoming courses.