I do this alot for a friend of mine. He gives me the plane and pays for everything I need. If he is not in a hurry, I don't charge him a thing. He'll usually give me a few gallons of fuel or things that I may need that is related to my style of planes and flying. Maybe about $100 worth of stuff might be nice. Like a grab bag with things you know he will need or use would be a nice gesture.

An Arf is not that big a deal like a kit would be. If it were me and you showed up with a bunch of stuff, I'd be fine with it.