A book called "Go Ahead - Take the Wheel", subtitled "Road Racing on Your Budget", by Dave Gran. Actually Dave if a friend and former competitor of my Brother's, until he changed classes.
The guy writes well and gives a comprehensive outline of the costs and hassles of being a weekend warrior. Motorsports are never cheap, but can be much less than you would think. Well, maybe more than you think.......either way, this book lays it out in realistic terms.
http://www.goaheadtakethewheel.com/WatchtheAction!.html
Oh, and there's a picture of my Brother's last race car on the cover.