Note 2 - Net Income Per Share - Net Income Per Common Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net income	$ 1,755,232	$ 803,316	$ 2,393,014	$ 2,587,767
Weighted average common shares (in shares)	13,430,503	13,522,755	13,441,619	13,559,704
Dilutive potential common shares (in shares)		75,827	31,504	171,241
Weighted average dilutive common shares outstanding (in shares)	13,430,503	13,598,582	13,473,123	13,730,945
Net income per common share:
Basic (in dollars per share)	$ 0.13	$ 0.06	$ 0.18	$ 0.19
Diluted (in dollars per share)	$ 0.13	$ 0.06	$ 0.18	$ 0.19