they do these in Ohio all the time... there are several each year... they typically raise money for a charity so a lot of the busses are sponsored.. they buy a lot of rusty michigan and PA busses cheap.. its a great source of bus parts though.. as a lot of guys drive their busses to the derby town and then strip them there.. some derbies require the windows come out.. a lot of busses still have good engines after the derby believe it or not.. the first thing to go usually is the air-brakes compressor and transmission lines which pretty quickly the bus just stops.. even though the radiators get damaged they dont often over-heat as they are idling more than being hammered... the last ones to be in the derby usually have the most damaged engines and are usually hydraulic brakes... occasionally you;ll see a rather good bus go into one of these..
ive watched a few.. they are a hoot and the crowd really gets into it..
-Christopher