I had a similar situation involving my father back when I was in college. I never charged my own family for computer advice before. I was worried when my father got a new PC, then was always bugging me with questions about it. I felt bad, but it began taking so much of my time away from school that I basically said that I would have to charge some money for my time.

Bad idea - that was met with so much bitching and complaining. Even my mother disagreed with me, and she had just divorced my father a few years before. So, yes, it wasn't about the money, it was more to do with the fact that my time was being used up on multiple occasions to fix small issues or answer questions. I probably would not even have pressed the issue except for the fact that I was poor and jobless. I ended up doing the work for free.

I like the "pay in trade" idea, like if I help out a friend or relative with their computer, I wouldn't expect anything in return, but would be happier to receive something, or some service back in return that they perform in their profession or skill.