I find it ridiculous people spend big $$$ on a race car then won't spend $20-50 for a professional photo to capture the moment. I know many old racers who wish they had photos of that special car at it's best.
A really good WA based motorsport forum run by and supported by some of the best photographers in the business is
www.speedwest.net . Have a look around those forums you will see a few guys doing the same as you. It's sorta the unofficial forum of the WASCC crew as well.