I'd be very interested to see your experiments.
I think you can buy toy airship kits, with propulsion and steering, for $30-50, but unmodified they probably don't have the lift to carry a klicky as well as all the motors, battery, and so forth. You'd need to make your own balloon, or connect two or three together. Making your own can be done, but it's the devil to glue the seams and make it helium-tight.