I had my Corona alloys sandblasted by a local industrial company. Holy *%#@, they almost ruined them. They were extremely rough (like sandpaper) when I got them back. I spent a week of spare time re-polishing them with a rotary wire wheel and fine grit sand paper. They actually look cool raw like this now. I am going to send them out to be powder coated as soon as I figure out what color I want. For about $50 I can get gloss white, copper-gold, bright yellow or for an extra $50 a chrome-look coating). Silver, boring. Black, no way - looks like someone stole your hubcaps from a distance. I'm leaving the center caps off and using chrome lug nuts. Mine short ones work, but some brands stick out too far and won't let the center caps fit. I do not know how well paint will stick to alloys. My brother painted his 5.0 mustang wheels black (cop-car look). He has to touch them up a once a year from the stone chips.
Ben