If you don’t feel like working for the man and you want to start a nice clean quirky business, take a look at Bathtub Racers. They promise to offer a “unique driving experience and a down-and-dirty adrenaline rush that won’t wash off for days.” You can start off with 2 bathtub racers for $10,000 or save some cash by buying in bulk, 4 for $19000 or 6 for $27000. Unfortunately, batteries are not included. If you don’t want to waste your time with designing your own course, you can purchase the inflatable course(pictured below) for the low price of $10,000.
From the site:

Totally re-defining the idea of good, clean fun, the Bathtub Racer is the culmination of hundreds of man hours, and countless packets of soap, in the pursuit of innovative engineering excellence.

[via Random Good Stuff]