It is a quick and easy job if the shop has the correct fixture and a CNC mill. If you take it to a shop that doesn't have a fixture then it is going to cost a bunch. So the answer is that it all depends.

Do you have the matching fuel rails already or do you need the fuel rails machined too? If you have the fuel rails already then you need to give those to the shop so they can make all of the holes line up. If you have a drawing showing the hole pattern then that will save a bunch of time. What about the brackets to hold the fuel rail? Do you have them or do you expect the shop to fabricate something custom?