I don't think people are charged $20,000. Alexis Ohanian is raising money for the program, and he has a goal of $20,000. That fundraiser also says that the program awards partial and full scholarships.

Also, the NY Daily News is saying they are trying to raise $1,000,000 for the program to pay for 100 students. So that would put the cost at around $10,000 per person without scholarships. http://www.nydailynews.com/new-york/queens/queens-techies-fu...

I didn't see any figures about how much the average student paid though. I would be interested in that figure.