Note 2 - Significant Accounting Policies - Schedule of Earnings Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Net income applicable to common shareholders	$ 725,457	$ 1,476,248	$ 1,525,663	$ 1,884,463
Weighted average shares, basic (in shares)	19,357,000	19,526,000	19,370,000	19,508,000
Warrants to purchase common stock (in shares)	325,000	190,000	288,000	145,000
Weighted average shares, diluted (in shares)	19,682,000	19,716,000	19,658,000	19,653,000
Basic (in dollars per share)	$ 0.04	$ 0.08	$ 0.08	$ 0.10
Diluted (in dollars per share)	$ 0.04	$ 0.08	$ 0.08	$ 0.10