I don’t know, I imagine they can’t stop you, but it will have to be the exact textbook and you don’t know what it will be until school starts.
All I know is somewhere, someone is making a killing off of this and there doesn’t seem to be a d*mn thing we can do about it.
If you think about it, take one of the books and run the ISBN code on the back through Amazon and see if the exact book is available and for how much. It would be interesting to find out what the cost difference is