That's not a bad price for 11 books.
TCS and I pay about $150-200 for each text book. There are very rarely any used books available. In my computer classes there are never used books available. They use new ones every year. We don't sell back very many books either.
With many of the courses, the book cost includes a DVD and/or an access code for online lab work. Even if a student can find a used text, he still has to pay for a new code.
Many of the computer courses use books that are published exclusively for our college, so that limits sources, too.