Have you heard of the Detroit Maker Faire?

there is a 500 dollar limit to what you can pay for stuff you get a kids toy faster with

"With a limit of $500 spent on modifying a kid’s Power Wheels car – hacker spaces race for the championship in the 2012 Power Racing Series.

The innovative racing series makes engineering entertaining and approachable. The goal of the Power Racing Series is to advance technology education and encourage people to try something new. (And have a good time, too.)"

found on http://www.makerfairedetroit.com/