Not too sure how Grado finished the cups, but you could take it to an Auto or machine shop of sorts and see if they could re-finish them. The problem is, they would want the drivers and sleeves removed so they could work only with the metal.
I might be an oddity of opinion, but the aged look kind of suits them in my opinion...:)
I've looked at this from a photographer's perspective, and they're really hard to photograph aesthetically, with their current looks, but i think you're on to something.
of course there's no way i'll be taking them apart. my RS-2's drivers are loose, as i can't find a suitable glue to replace the original one.