I get what you're saying, and I know the old argument about seat time in autox, but the cost difference is substantial when you factor in tires, travel costs, etc. I don't see how you can compete in MC without dropping $1500 for the first half of the season alone. Even though I get less seat time in autox, I can participate weekly with a half-day commitment and a set of tires will last me 6-8 months, minimum.
Overall, its silly to compare autox to track, since they are apples/oranges. I'm considering trying a few MC events, but will not be able to travel enough to make the series worthwhile.