As someone who worked over 11 years in the textbook industry, our community member suggested you always ask the teacher these questions:

1. Can I get by with a previous edition of the textbook?
   

2. If the school has "Inclusive Access," meaning the cost of your books are included with your tuition as a per-credit-hour fee, ask if you need to have that. You have to be able to "opt out" to be compliant with the law.
   

3. If the publisher of your E-Book is Cengage, you may be able to find it on "Cengage Unlimited," which is a program that includes most of Cengage's e-books for a flat rate for either a semester, a year, or two years.
   

4. For books with access codes: Do I need the code? You may be able to find the book cheaper without the code if it isn't needed.
   

5. Some publishers/schools make "custom" books for that specific school/class, so you cannot find it elsewhere at a discount. What makes them custom may be a different order of chapters, a missing or extra chapter, and the idea is sold to instructors as a way to save that students money. Ask the instructor if there is an equivalent edition that you could purchase used at a discount.