I don't understand why you came in here to say little more than "this costs money, I don't like it", while taking a shot at people who have earned disposable income.

Do you really think Khan Academy is free? It's only free if you have electricity, a computer, and a broadband internet connection. Knewton really adds only a tiny amount of money on top of that massive infrastructure cost.

Even if you think "oh, just go to the public library!" I would respond, "how, with what money or means?" That's not free either.

None of these things are "free". I feel that you've simply taken an arbitrary ideological stance where a company producing materials and asking for money to compensate them is somehow less "preferable".