I've had excellent results using low VOC acrylic spray paint from Motorcar Colors in South Jersey/Delaware. Excellent by my definition means a solid marriage between quality and cost, and at under $30/can for true BASF Glasurit match from the code under the seat, you can't go too wrong. The product is called SEM Custom Fill. I used duplicolor primer, the SEM and the SEM 1 part clear, but if you're putting it on a tank or anything that could conceivably see fuel, you MUST use SprayMax clear. The SEM can even had the metallic chips that give the BMW metallic colors that unique depth.
Problem is, Motorcar Colors doesn't ship product and I have to ride an hour to get it. But there must be an auto paint specialist near you that deals with Glasurit. I found these guys by calling Glasurit and asking who the local dealer is. They gave me a few names and MC was the closest.
There's also Colorite but they couldn't put what I wanted in a can, and were more expensive than the local guys, plus the shipping.
Maybe my standards are lower than the average Joe, but with good prep, good application, and buff and polish with 3M compounds it's a damned good match and has the same gloss as the original for about an $80 investment for tank and Parabellum fairing. So, the SEM acrylic urethane gets my vote...make the call to Glasurit of more info.
If you want to spray from a gun, call Holts BMW in Ohio -- but then you're talking in the $400 range just for the color.