Note 15 - Stockholders' Equity - Summary of Changes in Stockholders' Equity (Details) - USD ($)	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Balance	$ 33,489,207	$ 35,184,039
Share-based compensation expense	$ 133,845	138,461
Issuance of common stock upon exercise of stock options, net (in shares)	1,600
Issuance of common stock upon exercise of stock options, net	$ 2,528	159,518
Other comprehensive loss	(54,335)	(8,031)
Net income	1,045,940	(1,683,253)
Stock buyback	(1,621,022)
Balance	$ 32,996,163	$ 33,790,734
Common Stock [Member]
Balance (in shares)	33,176,146	31,158,436
Balance	$ 332	$ 322
Issuance of common stock upon exercise of stock options, net (in shares)	1,600	90,852
Net income
Stock buyback (in shares)	(588,425)
Stock buyback	$ (6)
Balance (in shares)	32,589,321	31,249,288
Balance	$ 326	$ 322
Additional Paid-in Capital [Member]
Balance	90,251,145	87,956,839
Share-based compensation expense	133,845	138,461
Issuance of common stock upon exercise of stock options, net	2,528	159,518
Net income
Stock buyback	(1,621,016)
Balance	88,766,502	88,254,818
Retained Earnings [Member]
Balance	(56,516,895)	(52,771,853)
Net income	1,045,940	(1,683,253)
Stock buyback
Balance	(55,470,955)	(54,455,106)
AOCI Attributable to Parent [Member]
Balance	(245,375)	(1,269)
Other comprehensive loss	(54,335)	(8,031)
Net income
Stock buyback
Balance	$ (299,710)	$ (9,300)