Unsurprisingly I leap to the defence of the underrated Auster!
Hourly costs - around £25 for fuel and oil
Fully comprehensive insurance - £750 / year
Annual maintenance - about £1,000 including the Annual Inspection
Flyin Dutch I don't think the ground handling is any worse than any other aircraft with a shopping trolley tailwheel (unsteerable and fully castering). It did tend to wear out the brakes until I fitted a steerable tailwheel though. Now I prefer the ground handling to that of the L4 I used to have mainly cos the brakes are better.
I've got a Cirrus Minor engined J1 Autocrat that trundles along at around 90 mph burning 4 gallons / hour. It has enough grunt to get two fairly chunky chaps and fuel out of a 550m strip quite comfortably. It is cheap to run but as kingy says, they cost an arm and a leg to rebuild. However, like all engines on a Private C of A, they can be run indefinately as long as the compressions are good and there is no evidence of bearing metal in the oil filter.
Regarding the PFA / C of A thing, as long as you don't want to modify the aircraft there is not a lot of difference in the cost of running it. If you don't do your own maintenance the difference is tiny. A lot of people don't realise that they can do the maintenance on a C of A aircraft themselves under the supervision of a licensed engineer.
To sum up, I prefer the over engineered Auster to the L4 Cub. If the engine does eventually die on me in a spectacular fashion I'll probably go down the same road as Oscar Deuce and fit a Lycoming 0-320 150 hp engine. These can be obtained reasonably cheaply, the mod is a well known conversion and it makes the old Auster climb like a scalded cat!!
PS Drop me a PM as I might be persuaded to sell my Auster cos my hangerage charges have become extortionate.