They are actually not too hard to do yourself depending on how bad they are. You can't really polish too much or you'll start going through the plating layers. Once they are polished spray the whole thing flat black a few times let the paint dry well. Then there are two ways to take the black off the face. Either hit it with super fine sandpaper, I can't remember off hand what grit I used. Or you can softly rub them over a paper towel soaked in laquer thinner.

That's for the emblems with the black background and are the only types I've done.