But what goes in to total annual cost? Gas? Parts? Ranges? People?
USN usually uses AVDLR which includes flight hours (gas) and parts to measure flight hour cost.
But if you're looking at including everything that it takes for the operation to execute your price can go up a lot. For the program I work on I can include contract maint cost, gas, parts, range, telemetry, engineers, etc and drive the cost/fly hr up a lot. If we fly less the cost will go up because a lot of these costs you have to pay regardless of whether you fly or not. For instance we have to pay an annual maintenance that is based more on the amount of people we need then how much we fly. So if we pay $1mil for maintenance for the year and fly 1 hr our flight hr cost is 1mil/hr. If we fly 1mil hrs the flight hour cost is only $1/hr.
This simple example only scratches the surface of to cost out flight hours.