I'll be surprised if the iPad doesn't dip to $400 this year, and I'd be shocked if schools don't get bulk discounts on top of that. And there's no reason to assume that $15 is the absolute minimum price - we'll see free alternatives in the near future.

I'm jealous of the kids - I remember lugging around 30 pounds of books and a bulky binder everywhere, and even then making frequent locker runs. And I have few fond memories of textbooks in technical subjects, where a few simple demonstrations (now embedable!) could often go further than a mountain of diagrams and words.