It just seems sprint karting in particular is the most expensive thing going. I just pulled up all kinds of entry forms online – ama road racing, late models, quarter midgets, legends cars, etc and all are considerably less. Most have no spectators. All require the use of a track and professional staff. Most pay back. Heck, even the dirt oval kart race at Daytona cost less than half of what the sprint race was, and paid back. Likely had more overhead too because it ran for longer hours and required track prep.
If I go to a regional race it is the same track rental over 3 days, I park over the same chunk of grass, just as many paid officials (usually staff from the track), same ambulance, same everything really, but fewer entries. And it is usually about a third the cost of a national race. Of course nobody is being flown in and put up in hotels for 4 or 5 days.
Assuming staff gets paid the same whether at a regional race or national race, then the only major difference I can see between regional and national is having to bring in and house staff. What does it take, about 6 people? So figure about $10k to get them to the race and back, feed them well, and put them in a $150/night hotel. So if a race has 200 entries then it means $50 of extra overhead per entry. So this realistically explains $50 of it.
I am only teying to talk this out so perhaps we can figure out why our little corner of motorsports is so expensive vs others. Obviously as prices go up, entrys go down. As series divide, entrys go down, so prices must go up which means entrys will decline even further. Can we tell series we want to give up different things to bring the cost down?