You will probably need to include more specifics. For instance:
1) What are they? Cap n ball, Colts, Rugers, Piettas
2) What do you want done? Tune them, smooth them out, time them, hammer conversion, cylinder conversions, cap rakes, transfer bar removal, etc..
3) What is your ultimate goal? Speed, smoothness, style points, ease of operation, etc.
You might be better off to ask for people that have a good reputation for quality work and, once you have two or three names, talk to them personally to determine what you are trying to accomplish and what you can afford.
The reason I say this is because you can buy a pistol for $200 and easily spend $600 getting it modified in all sorts of ways.