I think my LHS had a pretty good approach to on-road: There's a stock class for the RTR RC18R minis, an upgraded "super-stock" class, and 1/12th scale races on the same night. There's a pretty steady progression for many people... grab an 18R because it's cheap, progress to super-stock, all the while watching the pan cars run... only a matter of time before they're ordering a kit.

(I know, because it happened to me! heheh)