Good question.
I don't know what James is up for but this is a typical, budget cost for an event:
License $100-$400
Entry $200-500
Tyres $300-500ea. So $1200-$4000 depending on which tyre and if you can afford 2 sets.
Fuel $100-$200 for 98 or e85. $300-$400 for race fuel
Brake pads $200-$500 per set
Fuel to tow the car to the track $200
Driver and crew accommodation $50pp per night
Driver and crew food $50pp per day
Driver and crew booze: depends on win or lose. Lose is more expensive
Plus prep on the car, say $5000-$100000. Or 3-5 times that for a front running superlap car.
So, I reckon every 50 bucks someone can spare will help a great cause