I would say $50 a year is reasonable... The problem is that every track needs to participate. Right now, you have some ROAR tracks, independents, etc so no consistency.
When I raced BMX, every track was either ABA or NBL associated. Therefore, it was easy to keep track of who was an expert level rider, so no sandbagging. You got a card with your level and that was that...
IIRC, you could only race novice one year and then they bumped you to expert. The classes were beginner, novice, expert and pro (probably only like 50-75 true pros). After you won your first beginnner race, you got bumped to novice and coudl stay there for a year. Then you got bumped to expert which was a big wake up call since expert consisted of EVERYBODY from guys who weren't all that great to the really fast locals to the nationally ranked factory guys with full rides. It all got sorted out in the qualifying motos with the fastest guys quickly rising to the top and the slow guys getting eliminated.
What was funny though was that we had sandbagging novices who would race the full year going to nationals to get a national title in the novice class. We used to call them Pro Novices. Some had sponsorships and everything. They really were fast enough to be a mediocre expert. They could only get away with it for a year though before they automatically got bumped to expert and then quickly got their asses handed to them.
This worked well because the really fast non sponsored guys would have a good day and wow everyone by beating a few factory guys and they would get their moment to shine and ultimately pick up sponsors.