Motomummy has the marchesini wheels for like 2 grand...i havnt looked around for them though but a few of the guys around here have them on their bike so they could definitely help out with this...maybe they'll chime in soon
Who gives a shit what everyone else says, if you like em buy em. I don't know if I would put em on my bike but I do think they look sick. Haven't seen a set on an R6 but here's a R1 Roland Sands built.
I believe that the Yeller R1 that someone mentioned Roland built is on the Yamaha commerical. That bike is sick. Not really my style, but for something to cruise around on, and not care about handling/braking, I would pimp it.
For street riding they are a waste of money unless you want them for pure bling. It is much cheaper and can be much more creative to have the stock wheels powdercoated the color of your choice. I have Marchesini forged magnesium rims on my R1 and before it was turned into a track only bike, I could hardly tell the difference on the street.