I just had parts done at a shop here. i went for a tour to see how they finished the plating. and what i saw was belt sanders buffers and hand grinders. the owner told me that they dechrome the part clean it in a bath making sure the part was clean an depending on the metal what process they used. steal was ground down to 320 grit then they may even buff before they copper plate. the owner saying that the part would turn out however it looked going in but have a mirror finish. most places will not give you a set price but ballpark because of the labor and how good the piece is.
and the pits in metal all have to be filled one at a time so that is why it cost so much. the copper plating will fill the 320 grit marks then they can buff the copper to make it slick. they dipp it twice in the copper plating. before going to nickel then chrome. if you want his number. Rod was a super nice guy i'm sure he would be glad to answer any questions. jonathan