they do not use helium, they use a large propane or natural gas burner to heat the air inside the balloon, thus making it less dense, and making it float. It will cost around 3000 for a private license, or if you'd like to do it for hire, about 2 thousand more. With pollution, the balloons aren't a great method for transit, but the NG gas burns much cleaner than gasoline, or jet fuel.
