Hi QPJ,
first of all, forget about bringing a bike to China.
Very much depending on where you are going to live, China can be motorcycle heaven

or hell

.
After you got your work permit and residence permit (formerly called Z-visa), you can get a driver's license (procedures vary in different places).
Things go fairly easy in Beijing and can be a PITA in other cities.
There are, let's say, 4 groups of bikes available, which can be legally registered:
1. The < 200 cc class you can find everywhere and they go for 5k to 8k RMB.
2. The 600cc Chinese made Jialing, which is quite a nice bike, carries a price tag of 30k RMB.
3. Price range for the CJ sidecars is 8k to > 50k, depending on the condition of the bike, but they may be difficult to register in some areas.
4. The imported big bikes start from about 100k RMB. To my knowledge, to date BMW, Ducati and HD have dealers in China.
Depending on the place of rego, the plate costs from 1k to 20k RMB.
Check
this out for more info on riding in China.
Remember, every village has different rules!
Andy
P.S. Tell us where are you going to live.