The ones I saw at the Albuquerqe Ballon Festivle were home made. Looked like 2 end caps for round pipe about 30" in diameter with runners/joists about 36" long. This was covered with steel mesh or hardware fabric. It was mounted above a fire source of choice, mostly open hardwood fires, with a hand crank to turn as a rotissorie. I'm sure someone could fab up a power source to turn it. They turned it about 6 times a minute, IIRC. The BIG benifit was walking around and smelling the roasting chilies and jalepenos, stuffing ourselves with Mexican and Navajo food.
For cheap end caps (price of steel now) consider cutting the bottom of metal barrels or garbage cans. Or if you are a fab shop with tons of scrap, fab your own.
Dave, wishing he had a chilie roaster right now.