...the labor and effort to build a kit. I knew a hobby shop owner in Virginia back in the 1990's who built a number of kits for customers. He told me that he charged the price of the kit, plus ten times the kit price. As an example, a lawyer asked him to complete a tractor trailer model to use as a demo model in a court case. He charged the price of the kit, which was 45 dollars, plus 450 bucks for the labor. It also involved some scratch building, and was absolutely beautiful. I think the lawyer got a bargain.
On the other hand, I was approached by a veteran who didn't build kits but wanted a M109 SP howitzer that looked like one he served on. The local hobby shop got him in contact with me and he enthusiastically agreed to pay what I would charge him to build the kit, which was the old Italeri M109. I thought I did an outstanding job, and I even provided the kit out of my own stash. But he paid the 75 dollars I charged him reluctantly, and with much complaining. I was really hurt, because if you broke down the time I spent building, painting and matching to his reference it worked out roughly six bucks an hour. Because of that experiance, and the limited time I have to build for myself, I will not build for others. More power to those who do!