If you love go karts as much as I do, you'll also like this pretty cool video of a guy building his own kart. It shows that complete go kart kits are not a necessity when building these small cars. A lot of parts can be made by yourself if you can handle mechanics.

This guy built his own go cart as a part of his high school project. Speed is up to 50mph. He put in a 18 horsepower motor, while he got some of the other parts like wheels from yard sales and friends. Whole project took him up to 3 months of work, but he keeps going and improving. Great work, I think.