Note 15 - Stockholders' Equity - Summary of Changes in Stockholders' Equity (Details) - USD ($)	3 Months Ended						9 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
Balance	$ 33,770,543	$ 32,996,163	$ 33,489,207	$ 34,419,150	$ 33,790,735	$ 35,184,039	$ 33,489,207	$ 35,184,039
Share-based compensation expense	257,566	171,975	133,845	148,813	145,789	138,461
Issuance of common stock upon exercise of stock options, net (in shares)							35,282
Issuance of common stock upon exercise of stock options, net		42,644	2,528		26,200	159,518
Stock buyback		(550,000)	(1,621,022)	(500,274)
Other comprehensive loss	56,538	(69,091)	(54,335)	(211,426)	(4,482)	(8,031)
Net income (loss)	638,041	1,178,850	$ 1,045,940	(80,219)	$ 460,908	(1,683,252)	$ 2,862,831	(1,302,564)
Issuance of common stock upon vesting of restricted stock units (in shares)			156,115		125,000
Issuance of common stock upon vesting of restricted stock units	9,449		$ 2	842,006
Balance	$ 34,732,137	$ 33,770,543	$ 32,996,163	$ 34,618,049	$ 34,419,150	$ 33,790,735	$ 34,732,137	$ 34,618,049
Common Stock [Member]
Balance (in shares)	32,572,118	32,589,321	33,176,146	32,394,288	32,249,288	32,158,436	33,176,146	32,158,436
Balance	$ 326	$ 326	$ 332	$ 322	$ 322	$ 322	$ 332	$ 322
Share-based compensation expense
Issuance of common stock upon exercise of stock options, net (in shares)	7,000	26,682	1,600	468,801	20,000	90,852
Issuance of common stock upon exercise of stock options, net
Stock buyback (in shares)		(200,000)	(588,425)	(211,326)
Stock buyback		$ (2)	$ (6)	$ (2)
Other comprehensive loss
Net income (loss)
Issuance of common stock upon vesting of restricted stock units			$ 2	$ 5
Balance (in shares)	32,579,118	32,572,118	32,589,321	32,651,763	32,394,288	32,249,288	32,579,118	32,651,763
Balance	$ 326	$ 326	$ 326	$ 325	$ 322	$ 322	$ 326	$ 325
Additional Paid-in Capital [Member]
Balance	88,431,123	88,766,502	90,251,145	88,426,807	88,254,818	87,956,839	90,251,145	87,956,839
Share-based compensation expense	257,566	171,975	133,845	148,813	145,789	138,461
Issuance of common stock upon exercise of stock options, net		42,644	2,528		26,200	159,518
Stock buyback		(549,998)	(1,621,016)	(500,272)
Other comprehensive loss
Net income (loss)
Issuance of common stock upon vesting of restricted stock units	9,449			842,001
Balance	88,698,138	88,431,123	88,766,502	88,917,349	88,426,807	88,254,818	88,698,138	88,917,349
Retained Earnings [Member]
Balance	(54,292,105)	(55,470,955)	(56,516,895)	(53,994,197)	(54,455,105)	(52,771,853)	(56,516,895)	(52,771,853)
Share-based compensation expense
Issuance of common stock upon exercise of stock options, net
Stock buyback
Other comprehensive loss
Net income (loss)	638,041	1,178,850	1,045,940	(80,220)	460,908	(1,683,252)
Issuance of common stock upon vesting of restricted stock units
Balance	(53,654,064)	(54,292,105)	(55,470,955)	(54,074,417)	(53,994,197)	(54,455,105)	(53,654,064)	(54,074,417)
AOCI Attributable to Parent [Member]
Balance	(368,801)	(299,710)	(245,375)	(13,782)	(9,300)	(1,269)	(245,375)	(1,269)
Share-based compensation expense
Issuance of common stock upon exercise of stock options, net
Stock buyback
Other comprehensive loss	56,538	(69,091)	(54,335)	(211,426)	(4,482)	(8,031)
Net income (loss)
Issuance of common stock upon vesting of restricted stock units
Balance	$ (312,263)	$ (368,801)	$ (299,710)	$ (225,208)	$ (13,782)	$ (9,300)	$ (312,263)	$ (225,208)