Is this illegal? (School bookstore "monopoly"?)?

Many of my college cles require a "package" rather than just a textbook. The problem is that they don't say what is in it and the manager at the bookstore REFUSES to tell me exactly what is included in this package. This means that I HAVE to buy it from them. They aren't terribly overpriced, but this seems ridiculious and possibly illegal to me (monopolizing or something?). They are making me buy from them and I don't even know what I am paying for until I get it. Is this illegal? (Don't answer unless you know what you are talking about)