Welcome to Rctech .net!!! we're glad you came!
There are many things you can do in this hobby, and many more sub-hobbies within the hobby. some people do convert cars and other vehicles into different things, which from personal experience, is fun in itself.
a website worthy of looking at, www.ultimatetraxxas.com
, has many vehicles that have been modified for the better. the creator of the site has done many projects that are fun to look at.
unfortunatly, project cars still tend not to be as competitive as true racing machines. so, if you truelly wanted to start serious racing in R/C, then i would highly suggest getting a TC3, or other vehicle. off-road is lotsa fun too!
the hardest thing is getting your hands on a decent vehicle. but once you do, hang on to your transmitter! its lots and lots of fun!
Cheers, and good luck!