Because I'm a General Handyman/ OddJob Guy, I do get asked this often. Everyone who would ask me knows what I do and would expect to pay something.
However, family only gets to pay for materials. Depending on what the job is, neighbours and regular pensioners are charged at whatever whim takes me at the time. Freshly baked quiche, apple pie, scones, tea and cake, $20 for 'expenses' etc... It gives me a thrill to undercharge people unexpectedly. I do it because I can.
And that came about from 2 decades ago before I became self employed when someone did something very special for me and the kids soon after their mum passed. I asked why for free? and the lady involved said "Because I can".