How much time did you spend on the project? How would they have done it if you could not? What would the other process have cost to produce the same end result? I have 30+ years CNC and cad experience. Depending on the Job, Customer, and dificulty I try to charge (with a clear consience) min. 20.00 per hour and as much as 150.00 per hour. You want to charge whoever a fair price that they feel they have not been gouged but not so little you are being taken advantage of. You would hate to be over run with a job you only make 10.00 per hour on and not have time to run a 150.00 hour job and have to turn it down. It is also hard to raise your price to a customer. I tend to look at 20.00 per hour and add for degree of dificulty. On the cnc is where you can kick it up a notch. Our shop rate is 45.00 per hour. But I qoute the machine time conservatively and end up making usualy 90.00 to 120.00 hour. I have been taking jobs from larger shops than ours because they are slow to react and have higher shop rates (75.00 per hour). I started an injection mold tool shop and I have not one manual mill! Only cnc. The old adage is Charge what the market will bear. Be alittle bold and confident of yourself...If it was easy they would have done it themselfs. By the way neat project. My Dad was a radio operator on a B-17 in WW2.