Can't coat plastic but can do any metal. Can also polish most metal parts (some I just won't bother with, so ask for specifics).
As far as chrome color goes, I do that mainly for Fox Body parts and do large quantities at a time so I can do that color for anyone quite cheap. Other colors would be specific to however many parts you have done in it so it wouldn't be as cost-effective. Still probably cheaper than most places though, from my experience anyway. I'm just a guy, I'm not keeping a company in business by doing this stuff...and as such I get to undercut everybody, lol.