Try looking at this site, they look to be professional and have been around for a few years. Not sure what their prices are like though:

http://www.chang-jiang.com/bmw/welcome.html

G'day, I ended up using Jack From
CJ Sidecars. Contact details are: jack-high@163.com Ph+86 138 1676 1271
267－5 Chengjiaqiao Rd.,Minhang District, Shanghai www.cjsidecarclub.com
His prices were good, quality was good (CJ parts can be a mixed bag), he emailed me photos of the actual parts he was going to send, freight was reasonable & parts arrived quickly. He fixes my mates CJ in Shanghai & organises rides for CJ owners.He is a good helpful guy. Regards, Bill

Hi, not sure if I have what you're looking for but if interested in bikes and parts at a very reasonable price, email me and I can give more information
Maria