I would have done it for "free", finding the part that is, of course we would get the mark-up in the price of the part. Small business people go through this dilemma all the time, spending their valuable time doing things that aren't productive in their minds, would his time have been better spent actually producing "work"?
I have this discussion with my wife all the time. She often gets the question about how long it takes to make a piece of her work, (high end gold/silver jewelry) I said to tell them 30 years! The reality is that it has taken 30+ years to get her art to a point where she has the skills to produce something to the level of quality that her work has achieved......