chrome plating

The chineese can reproduce parts for less than we can have oem repaired.
Cast potmetal pieces need stripping then all the pits cleaned, filled, and reworked to shape. No one can predict how much labor is involved there.
Both stripping and platting produces hazardous waste. thus the waste disposal fees.
China and others don't have the environmental concerns or regulations we have. Their workers aren't protected from the health hazards related to lead and chromium either.
I really dont think the price quote would vary much from one company to another but I'm sure the quality of work and turn around time would vary.
Hope this helps