That is an interesting wrinkle Tomo, I suppose to be pedantic the cost of your flying someone else's aircraft (ie not hiring) is the fuel etc it takes to get wherever you're going; but as Darky says there are ways around it and it is difficult to see how you could come up short when all you're doing is volunteering your time as a favour. If I were in that position I promise you I'd find a way to make it work! Remember too that it's apparently ok charge the cost of flying yourself somewhere for work, to a client, in the same way you would driving there in a car. The way to do it seems to be a fixed charge per km, eg if you flew somewhere to fix a machine for someone instead of driving the ute there. Hoping to make use of this myself before long. The difference though is that you are using it as transportation for yourself.
As I understand it jump pilots operate under a specific dispensation, Ozzie n co can tell us more about it.
Edit: I see while I was chewing on my lunch the conversation moved on.