I did a quick search and didn't come up with anything definitive, so I'll post this.
I read the magazine Grassroots Motorsports (great mag) and I was wondering if any of you guys had heard of the $200X Challenge (X signifying the current year i.e. the next Challenge is in 2005 so it will be the $2005 Challenge). You only have a budget of $200X to spend and build the fastest streetable car you can, while retaining a real body and safety equipment and everything (there is also a $200X Locost Challenge for completely scratch-built cars). All the cars compete in a drag race, an autocross, and a concours judging.
For more info go to
http://www.grassrootsmotorsports.com/
And here's some pics from the $2004 Challenge (all of these cars were built from $2004 or less, and this is just a few from about 80 cars)

Rotary VW Beetle

V8 Honda CRX

V8 VW Microbus

Turbo Alfa Romeo Spider

V8 Corvair

MG Midget with turbo Ford motor