The guy at "Boots and Bits" saddlery would be your best bet. Think his name is Brian. Address;
Room 1721B, 17/F, Star House, 3 Salisbury Road, Tsim Sha Tsui, Hong Kong, NA, Hong Kong
Tel: +852 27350123
Fax: +852 27360031
Web: www.bnbsaddlery.com.hk
He has contacts with people running stables in Shenzhen.