Rocket-powered single-seat helicopter emits only water (wired.com)

Actually, $44/hour isn't so expensive - it costs ~$120/hr to rent a Cessna 172. Granted the $44/hour doesn't include the cost to actually purchase and maintain the thing, but what a small price to pay for your own personal helicopter :-D

I bought the plans for this tip-powered copter from the back of a magazine like Boy's Life about 20 years ago.