Note 17 - Quarterly Data (Unaudited) - Summary of Quarterly Data (Unaudited) (Details) - USD ($)	3 Months Ended												12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Revenue, net	$ 10,892,868	$ 7,220,626	$ 3,346,315	$ 2,356,926	$ 2,692,040	$ 1,530,244	$ 1,046,624	$ 1,376,872	$ 1,794,910	$ 1,804,614	$ 1,091,182	$ 1,162,218	$ 23,816,735	$ 6,645,780	$ 5,852,924
Gross profit	3,034,379	3,029,146	1,377,514	583,238	561,720	760,814	352,080	636,351	1,132,731	807,794	381,991	362,105	8,024,277	2,310,965	2,684,621
Net income (loss)	$ 567,439	$ 941,523	$ 213,140	$ (313,706)	$ 5,152,576	$ (8,095)	$ (464,444)	$ (47,189)	$ 315,311	$ 109,631	$ (276,663)	$ (270,656)	$ 1,408,396	$ 4,632,848	$ (122,377)
Per share amount (in dollars per share)	$ 0.20	$ 0.33	$ 0.07	$ (0.11)	$ 1.81	$ (0.01)	$ (0.28)	$ (0.03)	$ 0.19	$ 0.07	$ (0.17)	$ (0.17)	$ 0.49	$ 2.38	$ (0.07)
Per share amount (in dollars per share)	$ 0.18	$ 0.31	$ 0.07	$ (0.11)	$ 1.77	$ (0.01)	$ (0.28)	$ (0.03)	$ 0.19	$ 0.07	$ (0.17)	$ (0.17)	$ 0.46	$ 2.36	$ (0.07)