CG Lock is good, especially for as cheap as it is. I actually have a strap that I use for my torso, just a couple yards of seabelt material with a plastic clip that I put around my chest at the track. It actually works REALLY well, super cheap, no mods required, and you just unclip it when you're done.
Don't waste another minute waiting on parts, or anything else. Just get out there and start racing! You will suck at first, and you will be slower than many other cars, but the only thing you will regret is not starting earlier...