Note 2 - Net Income Per Share - Weighted Average Common Shares Outstanding (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net income	$ 2,994,568	$ 1,300,527	$ 4,243,623	$ 2,678,429
Weighted average common shares (in shares)	13,497,955	13,446,289	13,510,413	13,422,885
Dilutive potential common shares (in shares)	0	5,382	36,711	11,124
Weighted average dilutive common shares outstanding (in shares)	13,497,955	13,451,671	13,547,124	13,434,009
Basic (in dollars per share)	$ 0.22	$ 0.10	$ 0.31	$ 0.20
Diluted (in dollars per share)	$ 0.22	$ 0.10	$ 0.31	$ 0.20