I don't run one but I should. There used to be a company that made cheap ones but I think they stopped. I'd see if an upholstery/soft top/boat cover shop could make one. It doesn't need to be that fancy.
Neoprene isn't really a good idea. First off they are expensive. Second, UV will kill the rubber and fade the spandex/lycra. Third, neoprene is more like a sponge and will retain water. The rubber side will keep water off whatever is under it though. I'd rather have a cover made from denim though. Most of the ones you see from Warn and other companies are cheaper vinyl covers.