Well, let me tell you!
If you have 4 people, that's $784.81 per person... which does NOT include lodging once you get there, personal safety items (suit, shoes, gloves), and any other useless crap you end up buying at the track (we all do it...)
The bulk of our budget came from the ridiculous gas prices, and multiple trips to Seattle to pick up the car and the parts car (I wish prices were then, what they are now). Tires, high-end brake pads, Spare head gasket, and diesel for the truck to drag it 500 miles each way played a huge part as well.
Miraculously, we are $128.27 UNDER BUDGET for the car... It turns out parts on the 88 MR2 are worth quite a bit of money on ebay. We sold the interior for $125, and misc trim pieces for about $90. and that MOMO steering wheel we got in the purchase? $120 on ebay.