Note 3 - Revenue Recognition - Cumulative Effect of Changes for Adoption of ASC 606 (Details) - USD ($)	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Accrued liabilities	$ 650,513	$ 788,961	[1],[2]
Deferred revenue	645,470	690,905	[2]
Other liabilities
Deferred revenue	163,018	168,465	[2]
Retained earnings	8,848,684	8,414,570	[2]
Net Sales	21,842,097	23,522,631	[3],[4]
Cost of goods sold	15,022,223	16,966,633	[3]
Income tax provision	(26,503)	3,041,844	[3],[5],[6]
Net (loss)	$ 434,114	$ (3,411,220)	[3],[7],[8]
Basic (in dollars per share)	$ 0.06	$ (0.46)	[3]
Diluted (in dollars per share)	$ 0.06	$ (0.46)	[3]
Deferred income taxes	$ (13,276)	$ 3,041,405	[7]
Change in deferred revenue	(50,882)	15,638	[7]
Net changes in operating assets and liabilities		650,607
Cash provided by operating activities	$ 1,411,065	1,031,087	[7]
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Accrued liabilities		1,178,571
Deferred revenue
Other liabilities		155,702
Deferred revenue
Retained earnings		8,728,628
Net Sales		23,515,441
Cost of goods sold		16,933,431
Income tax provision		3,042,696
Net (loss)		$ (3,386,060)
Basic (in dollars per share)		$ (0.46)
Diluted (in dollars per share)		$ (0.46)
Deferred income taxes		$ 3,042,257
Change in deferred revenue
Net changes in operating assets and liabilities		640,233
Cash provided by operating activities		1,031,087
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Accrued liabilities		(389,610)
Deferred revenue		690,905
Other liabilities		(155,702)
Deferred revenue		168,465
Retained earnings		(314,058)
Net Sales		7,190
Cost of goods sold		33,202
Income tax provision		(852)
Net (loss)		$ (25,160)
Basic (in dollars per share)
Diluted (in dollars per share)
Deferred income taxes		$ (852)
Change in deferred revenue		15,638
Net changes in operating assets and liabilities		10,374
Cash provided by operating activities

[1] As adjusted for retrospective adoption of ASC 606

[2] As adjusted for the retrospective adoption of ASC 606 and ASC 842

[3] As adjusted for the retrospective adoption of ASC 606

[4] As adjusted for the retrospective adoption of ASC 606

[5] As adjusted for the retrospective adoption of ASC 606

[6] As adjusted for the retrospective adoption of ASC 606

[7] As adjusted for the retrospective adoption of ASC 606

[8] As adjusted for the retrospective adoption of ASC 606