From a pricing perspective, the relevant questions to me are:

1. Why is it ok to charge less for 2 endurance races than 2 sprint races?

(for perspective - I've been around long enough to remember when we started endurance races - 2003 I believe - and why the pricing was set so low. It was a method to bolster the safety fund to buy more air fence. That was it's sole purpose as I recall, and it was priced @ $50/$75 for 2 to get people to participate. This is back when all racing was on Sunday and Sat was practice only, so pricing was an incentive. No one "just" ran endurance back then that I recall)

2. If the price structure changed to level endurance races with sprint races, would the folks who currently only race endurance a) not race at all b) race fewer races c) race the same amount?

Only Option a) would appreciably lose the club $$ - but I think it's unlikely that many folks have built a whole program, with all the investment needed (even a shoestring one) just around entry fees that are <$100. If an extra $50-$100/weekend is going to cause them to completely drop racing as a hobby - then let's call it like it is, they should be putting $$ in their savings account, not racing.

I'm liking the idea of "a race is a race". Let them all drop into the normal pricing structure - that way there's no bias or incentive either way. People can run what they want...