Note 18 - Quarterly Data (Unaudited) - Summary of Quarterly Data (Unaudited) (Details) - USD ($)	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2017
Sales	$ 21,135,277	$ 19,771,137	$ 13,593,192	$ 11,878,700	$ 11,754,219	$ 10,892,868	$ 7,220,626	$ 3,346,315	$ 2,356,926	$ 66,378,306	$ 23,816,735
Gross Profit	4,460,559	4,450,389	3,486,578	3,018,441	3,225,832	3,034,379	3,029,146	1,377,514	583,238	15,303,967	8,024,277
Operating Income	2,383,150	2,471,279	1,816,945	643,085	1,290,945	1,414,462	1,308,925	265,896	(307,346)	7,314,459	2,681,937
Net Income (Loss)	$ 1,348,163	$ 1,497,079	$ 394,625	$ 373,752	$ 510,262	$ 567,439	$ 941,523	$ 213,140	$ (313,706)	$ 3,613,710	$ 1,408,396
Net Income Per Common Share - Basic (in dollars per share)	$ 0.50	$ 0.55	$ 0.14	$ 0.13	$ 0.18	$ 0.20	$ 0.33	$ 0.07	$ (0.11)	$ 1.29	$ 0.49
Net Income Per Common Share - Diluted (in dollars per share)	$ 0.43	$ 0.48	$ 0.13	$ 0.11	$ 0.16	$ 0.18	$ 0.31	$ 0.07	$ (0.11)	$ 1.14	$ 0.46