Henry (Raleigh NC)
Sounds like your undercut is an internal debate. Been there - in fact, I could have written your post word for word. I told the donor what I was going to charge for my time, estimated materials cost, and a total. He was OK so that is what I did.
My wife's view on the value of my time changed when she became involved in the facilities aspect of the church and started to understand what the market rate for expertise cost. Then my time charges seemed too cheap, even to her.