It really seems like there are a lot of people talking about what the market will do who haven't done even cursory studies of what market theory actually is. Do you know what market elasticity is? Without it the market can't work. That's why, for example, the market can't save us with health care. Health care is fundamentally inelastic (you'd pay any price for a life saving operation because without it you, to quote a movie, lose everything you've ever had and ever will have).
I believe we have a similar situation with education. You can't just opt out if it costs too much.
EDIT:
>No matter how important teaching is, teaching 20 kids per year is worth about $30K.
How do you know this? We know that we pay $30K/year now. We know that our teaching quality is awful. Doesn't that actually demonstrate (or at the very least strongly suggest) that it is in fact worth more?