Got an airbrush?
There is a kind of hobby paint called Alclad II. They make a chrome which looks very much like real chrome. You have to spray a gloss black undercoat before applying. It's a lacquer, so don't spray it over an enamel.
You can find it at some hobby stores. It comes in Gold, Chrome, Polished Aluminum, Steel, Gunmetal, Copper, etc.
If you've got to have it professionally done, most "chrome" on plastic nowadays is vacuum metalized-which is cheaper. You can find places that do this for custom auto detailing, like hood ornaments and such- check the yellow pages and call ahead to find out what size objects they can do.
A quick way to tell the difference between real chrome or vac metallized is to touch it. If it's cool to the touch, like metal, then it's real chrome.