I haven't seen any aftermarket rotisseries that are designed for home ovens, probably for the reason that you mentioned. It would probably be very expensive to design an electric motor and gear reduction system that could stand up to cooking temps. I'm sure that a manufacturer could design one that could be built into the oven though. If you find one or come up with any ideas, I'd like to hear about it.
"You wouldn't know a diamond if you held it in your hand. The things you think are precious I can't understand" STEELY DAN.