Note 2 - Net Income Per Share - Net Income Per Common Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 907,521	$ 1,492,979	$ 1,784,451	$ 2,980,433
Weighted average common shares (in shares)	13,589,109	13,309,181	13,578,178	13,298,874
Dilutive potential common shares (in shares)	214,588	272,629	218,948	279,556
Weighted average dilutive common shares outstanding (in shares)	13,803,697	13,581,810	13,797,126	13,578,430
Net income per common share:
Basic (in dollars per share)	$ 0.07	$ 0.11	$ 0.13	$ 0.22
Diluted (in dollars per share)	$ 0.07	$ 0.11	$ 0.13	$ 0.22