I spoke to Star Anodising in Dartford.... the receptionist didn't seem to think it would be a problem doing such a small job. Waiting to hear back from them about a proper quote so will let you know what they say.
ah cool, looking forward to seeing the result then! do you get to specify the RAL (or equivalent) of the silver you're after? I think I'd asked about getting some hub shells done in a bronze brown and they said it was too much hassle...
keen to see how this goes - been considering doing something like it myself but couldnt find an anodiser who would take on such a small job...