I've had custom wheels made before, and I have clients who have them made on occasion. It is neither quick nor cheap. There is also a LOT to consider in terms of fitment, back pad depth, caliper clearance, inner and outer clearance, etc...
There is a company in China called Brilliant Rays that I have been eyeballing for a while. They claim to make all sorts of wheels, 3 piece or single forged, they have 100s of stylers they claim to be able to make currently and have an engineer that will work w its you on a custom design also. Their "advertised" price per wheel is cheap (comparatively speaking). I was close to pulling the trigger on some custom designed pseudo BBS RS style wheels but the client went another route.