We started a new class beginning of this year. We called it the Club motor class, where the guys were only allowed to use the NT12T1 Engine. They could buy it anywhere, but the track owner also helped to get them for us at a very good price. Most new people were skeptical as they said it was a weak engine, and they wanted to go as fast as possible. (yes into the barriers)
When people saw that the lap times was almost just as good as with the top motors, almost everybody jumped on it and bought the engine. It was 3-4 times cheaper than top engines, and they could use it as a practice motor as well, and could pack their high end motors away for the big races. That has made sure that people don't disappear so quickly out of the hobby. Our biggest problem is not the cost, but the marketing of the sport, as we cannot race in a parking lot with all the noise from the engines, but I suppose that is another thread that we could start.