Have you considered Alclad? I did a prototype aircraft which had a highly polished wing. I used Alclad chrome over Tamiya gloss black and the finish rivals ANY chtome plated plastic part I've seen. A bottle of Alclad will run about $9, and slightly less for the Tamiya rattle can of black. You can do a bunch of parts for that investment, and you can do them as you need them, without having to round up a sizeable minimum order to ship off.