The cost of textbooks is a "racket".
I have had 2 children take dual enrollment courses at the local CC. The books have never been less than $160 each -- USED. This is for core classes such as "College Writing", "Intro to Computer Applications", etc. The College Writing textbook my daughter purchased was never used. (As in, the instructor NEVER assigned/used the required textbook.)
When a student tries to sell a book back to the college bookstore, they are offered pennies on the dollar. One usually makes out better trying to sell the books to a student taking the class the following semester. (and that only works if the instructor doesn't change books mid-year)