I hired one for 34 quid an hour last week, great value for money.
Saw a TV program on 747s a while back now and I seem to remember them saying that on an average LHR - JFK flight, a 747 makes half a million dollars profit on 2 sectors (there and back). Think it was half a million, it was big money anyway. Perhaps it doesn´t cost as much as you would first think?