Ditto that!!!
Now the mayor cost, as usual, is when starting to make these parts but once you got them and people know (we know...eh!) then you'll see them moving. Especially when you are covering a nitch market. For example the firing pin is hard to find, but when you look at it is very simple to make.
Just produce some fews and to test the water. I'm sure you'll feel it quite warmed!!!!