I know fuel got expensive, but I don't think AVGAS has really outpaced MOGAS in cost increase.

I asked one of them (via the evil facebook) this morning, and he said parts/overhauls going from "twice what it was on a car" to 10-20x what the equivalent part/service on a car was one of the reasons he now has his plane in a leaseback setup, and only flys 4-5 hours a month, tops.