Note 16 - Stockholders' Equity - Summary of Changes in Stockholders' Equity (Details) - USD ($)	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Balance	$ 35,381,349	$ 33,489,207
Share-based compensation expense	$ 158,327	$ 133,845
Issuance of common stock upon exercise of stock options, net (in shares)	83,343	1,600
Issuance of common stock upon exercise of stock options, net	$ 144,214	$ 2,528
Issuance of common stock upon vesting of restricted stock units
Other comprehensive income (loss)	85,314	(54,335)
Net income	620,327	1,045,940
Stock buyback		(1,621,022)
Balance	$ 36,389,531	$ 32,996,163
Common Stock [Member]
Balance (in shares)	32,949,987	33,176,146
Balance	$ 330	$ 332
Issuance of common stock upon exercise of stock options, net (in shares)	83,343	1,600
Issuance of common stock upon exercise of stock options, net	$ 1
Issuance of common stock upon vesting of restricted stock units
Other comprehensive income (loss)
Net income
Stock buyback (in shares)		(588,425)
Stock buyback		$ (6)
Balance (in shares)	33,033,330	32,589,321
Balance	$ 331	$ 326
Additional Paid-in Capital [Member]
Balance	89,571,641	90,251,145
Share-based compensation expense	158,327	133,845
Issuance of common stock upon exercise of stock options, net	144,213	2,528
Issuance of common stock upon vesting of restricted stock units
Other comprehensive income (loss)
Net income
Stock buyback		(1,621,016)
Balance	89,874,181	88,766,502
Retained Earnings [Member]
Balance	(53,731,903)	(56,516,895)
Issuance of common stock upon vesting of restricted stock units
Other comprehensive income (loss)
Net income	620,327	1,045,940
Stock buyback
Balance	(53,111,576)	(55,470,955)
AOCI Attributable to Parent [Member]
Balance	(458,719)	(245,375)
Issuance of common stock upon vesting of restricted stock units
Other comprehensive income (loss)	85,314	(54,335)
Net income
Stock buyback
Balance	$ (373,405)	$ (299,710)