I imagine Opex (running costs) would far outstrip Capex in this case?
Oh yes. Some fixed costs could be offset by airshow / film work, but probably not much. I'm guessing that fuel is in the order of 100 gallons an hour? Probably more. Out of my league, I'm afraid.
No-one said it would be cheap, but imagine the sound that beast makes!
QDM
P.S. There is a reason that G-DAKK Is being sold byt he receivers!