Ask them what about if you did the prep work? whats the finish you want? No reason they cant plate if you clean and sand as smooth as you like by hand. If you want them to do it all they arent really interested, its too fiddly for the piece and those tabs easily snap. Not worth dealing with an ahole job and client. So ask them how much you need to do first to prep for plating so they can just dunk in baths etc. Can be done but just like painting or powder coating, if you prep to a point (taking the damage risks yourself) they will be more than willing to do the job and on the cheap as prep work is considerable time sink and you are paying for that labour typically. Other option, draw the plans and get it fabricated and folded from sheet, since any coating its taking it away from stock anyway. or find a clean item / sacrificial machine to replace.