some quick advice from someone who has just entered the world of improved touring, and has also just built his own car.
When all the experienced guys told me to buy a prepared car, for some reason I didnt think it was good advice, and went and built my own. Of course, they had been there and done that, but for some reason I thought I knew better.
Someone once suggested on here that you go out and buy a car with your credit card, then pay it off slowly over time. This way your in a car driving right now, not waiting a year to get it built
I would recommend buying an ITB or C car for 5,000 or so (maybe less...). It will have probably close to 8 or 9 thousand invested into it, and you will be paying 50 cents on the dollar. It may not be a championship car, but will get you on the track.
Oh, and if you think your going to build a championship car, you had better allow for about a 15 to 20 thousand dollar budget. Even if you have some race parts already...
With your circle track experience you may consider a mustang, which race in ITB, as you may be more familiar and parts may match what you have...
matt