maybe an idea to look for a car that is for sale and already built. I dont know that you can build a street registered circuit car, with all the safety gear that you should have as well as rego for under 10k, but im sure some guys will get on here and tell you different, but realistically a cage, seat, harness, and good helmet will cost you between 3 & 4K. My kart cost me around 6k once i bought gear and spares.