Happy fran
Not a bad crack at the costings however you need to add £5/hour to cover engine overhaul and £8/hour for insurance.
The maintenance is real can of worms I am looking at the slow death of a once proud local FTO that is under pressure and letting maintenance standards slip, once an aircraft "gets away" from you in maintenance terms it will cost as much to get it back up to a good standard as it will to buy the thing in the first place.
The first thing to slip is the outward apperance, then reliability and if not checked safety.
Over the last few years I have spent a lot of money on maintenance of my fleet and now he costs have dropped dramaticly and reliability improved, I expect to see a number of other company's who have not invested in maintenance drop by the way side as the current situation bites along with the introduction of EASA part M that will drive up costs and tighten up maintenance practices.
What I do expect to see is a lot of cheap aircraft on the market as these issues bite, however all of them will be "old doggs" just waiting to cost the new owners a fortune in engineering bills.
The fact of the matter is that no one is getting rich in the GA business, under investment is rife and there is no room to cut costs just to as you say "put bums on seats" if you want to be in business next week.
If you a realy good deal comes your way I would guess that it will be cash up front and the company will be gone tomorrow along with most of your money.