I spoke with my SA at Chambers and he arranged to have their guy do it for $100 per wheel. This is not the perfect job that Rimpro will do (complete refinishing) but will be good enough not to notice. I'm going to give this a try and if it doesn't work out may go the Rimpro route. Thanks NSM for the offer!
BTW, unfortunately they told me that the M3 OEM 18 and 19 can't be done this way. The paint on the inside is hard (nearly impossible to match) and the polished part is also hard to fix without a complete refinishing.
Fortunately for me this is for the wife's 335.