So far, this is what I've discovered can be registered / plated in Beijing (besides the usual suspects of Harleys & BMWs). One dealer's prices in Beijing

Yamaha YBR 250 - 25,800 rmb

Honda Shadow (150 cc) - 15,000 rmb
Honda Fighthawk (150 cc) - 12,800 rmb
* didn't Honda used to sell a bike called the "Nighthawk"?

Regal Raptor 350E-6C - 25,000 rmb

Kymco Venox (250 cc) - 59,800 rmb
* interesting bike

Various scooters, including:

Kymco Like (180 cc) - 13,800
* becoming very popular in Beijing - see lots around, post license plate lottery system

Jialing JH600 (still not sure if Jialing applied/passed C3).

Please add to this list, as you find information.