The Mac Observer:

By comparison, you’d spend around $800 for an iPad 2 and a new textbook each year for those four basic courses. You’d get more up-to-date materials, interactive learning, and a smaller footprint in your luggage for those long-distance field trips. And, you’d spend half as much for that learning experience as you would using traditional books.

Interesting, I hadn’t considered the impact on home schooling.