How much would I have to pay you for a day of teaching kids how to program?

I'm thinking about launching a business around this idea, so I wanted to get some good opinions.

Here's mine: I'm a senior-level Rails/JS dev, and I'm not really into the whole "do good things for free" thing. I think for 8 hours on a Saturday I would do it for $200, or $25 an hour.

Let me know your honest opinion. I would appreciate it a lot, for real for real.