Try calling the local and surroundings ISD's in your area, that's where alot of the buses come from in low budget movies :D
Also check the city auto impound, I mean, there are still some hippies driving those around, and after all the weed possesion counts they're sure to lose either the flowerdy bus or the peace twinkie, and as I'm sure you all know, the hippies always choose the twinkie over the bus :confused:
-Searge