I'm going to be dropping some stuff off at the blaster/powder coating place I use hopefully in a couple of weeks. I plan on asking them how much to blast and powder coat my 20" SHO wheels. I can report back here once I get a price.
I'll be doing mine probably fall of this year when I switch to an A/S tire. I'm thinking some kind of matte black, gunmetal or dark gray, not 100% sure yet.