Remove the internals yourself and call around to local jewelers.
Keep your distrust to yourself. While I understand it on a forum, it's pretty rude from a professional standpoint for anyone who has the equipment to plate it. If you came to me for that job in person and started questioning my integrity to work on your $200
ecig while I work on people's stuff worth many thousands of dollars I'd refuse it because I couldn't trust you to not be a constant headache over me trying to do you a favor outside of my usual work.
As it is I simply wouldn't do it, I hate plating simple things let alone steel
Note that plating is pretty thin and will wear. As it wears it will show the base colors. This will be something that you need to repeat, probably often. Judging from some rings I see and the use an
ecig gets possibly once a year.
Although once the chrome is gone a pen plater may work so you may not need to remove the guts in the future, IF you find someone with a pen plater.
If you're expecting a heavier plating I have no idea where you would look for that for custom work. Maybe look for custom car parts platers.