Note 17 - Net Income Per Share - Basic and Diluted Loss Per Share (Details) - USD ($)	3 Months Ended				6 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019
Net income	$ 301,575	$ 620,327	$ 1,178,850	$ 1,045,940	$ 921,902	$ 2,224,790
Basic income per share (in dollars per share)	$ 0.01		$ 0.04		$ 0.03	$ 0.07
Diluted income per share (in dollars per share)	$ 0.01		$ 0.04		$ 0.03	$ 0.07
Weighted average shares outstanding - basic (in shares)	33,094,596		32,584,952		33,036,786	32,738,871
Assumed exercise of dilutive options (in shares)	638,023		492,303		672,046	533,293
Weighted average shares outstanding - diluted (in shares)	33,732,619		33,077,255		33,708,832	33,272,164
Share-based Payment Arrangement, Option [Member]
Antidilutive securities (in shares)	1,602,477		976,750		1,602,477	976,750