Other payables and accrued liabilities (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Other payables and accrued liabilities [Abstract]
Accrued expenses	$ 2,989,020	$ 4,348,657
Royalty payable	965,639	877,905
Sales deposits received	794,603	1,196,711
Other payables	599,871	517,790
Other payables and accrued liabilities	$ 5,349,133	$ 6,941,063