You are right - it has been asked before, and it's one of those how long is a piece of string questions.
You need to nail down the following variable first before asking the question:
Type - acquisition cost
Projected Hours each year.
Use of aircraft - online or private? VFR or IFR? This will also affect:
Insurance (use of acft / experience level)
Prop/Eng HTR?
Hangared? Where?
The more hours the cheapr per hour cost to absorb the biggies - maintenance and allowance for prop/engine overhaul, and insurance. Fuel is not as big a cost as you thought (unless you are getting a BIG thirsty single)