I will never say I have the best answers or opinions, but I've always felt that USAC should take a look at a few strategies to help reduce costs all around on pavement and dirt.
Carbon Fiber and Titanium: Outlaw it, there is no real need for these materials. I know in the midgets a steel drive shaft was around $100 or so, while a Ti drive shaft was around $750 or more, then they had the carbon drive shafts for even more. Throw in a carbon body kit and a ti bolt kit and you are looking at a couple of grand extra compared to sheet metal/aluminum bodies and steel bolts.
Shocks: I think this is an area where things have been allowed to get a bit out of hand. Do the cars really need a set of shocks that cost $1000+ per corner? Go to a rule where the shocks are single bodies and can be rebound adjustable but not in car. People will always find ways to build there own and spend more, this is where I don't have the best answer but I am sure some people could come up with a cost effective and good handling shock package.
Tires: As has been mentioned in this post already many times, tires are just a given to be expensive with pavement. The only thing I could see here is to restrict everyone to have to only have 2 sets per race day. Buy them at the track only kind of thing.
General: Have a spine when enforcing rules. I don't just mean engine rules or weight, but the whole rule book. USAC never checked a lot of things after the first race of the year. At the very least enforce the safety rules! Considering recent events, I think now would be a really good time to start enforcing the head clearance rule. I think in the midgets it calls out 4 inches minimum from top of helmet to highest point of the cage. I know for a fact that a lot of drivers are no where near that number.
Testing: We used to test a bunch when running pavement midgets. It helped a lot, but it wasn't totally necessary. It could be argued, but I would say to not allow it.
Beyond that I don't see any major ways of saving costs for the teams. There is a big problem with getting fans to have any interest, I am not a marketing guy so I don' have much to say for how you could improve the fan turn outs, but I agree that without more fans bringing money, it will be difficult to see any purse increase.
I loved racing pavement, I prefer dirt, but pavement had it's own very unique challenges. My opinion, dirt racing is more driver and less car whereas pavement racing is more car and less driver. On the dirt it was easier to take a 10th place car and get 5th, on the pavement it was a real challenge to take a 10th place car and get 9th...
Also, I think getting all three series (midget, sprint, crown) together at more events is a better way to get cars and fans to show up. Why they got away from triple header events is beyond me.
Just food for thought