Note 7 - Business Segments - Segment Reporting Information (Details) - USD ($)		3 Months Ended		6 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Net revenues		$ 19,456,000	$ 15,704,000	$ 39,666,000	$ 33,199,000
Depreciation and amortization		759,000	686,000	1,469,000	1,428,000
Stock-based compensation		341,000	205,000	605,000	468,000
Operating income		3,274,000	2,214,000	7,911,000	5,041,000
Operating Segments [Member]
Depreciation and amortization		640,000	567,000	1,247,000	1,180,000
Stock-based compensation		101,000	4,000	177,000	80,000
Operating income		5,029,000	3,565,000	11,346,000	7,800,000
Segment Reconciling Items [Member]
Depreciation and amortization		119,000	119,000	222,000	248,000
Stock-based compensation		240,000	201,000	428,000	388,000
Operating income		(1,755,000)	(1,351,000)	(3,435,000)	(2,759,000)
Coins [Member] | Operating Segments [Member]
Net revenues	[1]	10,700,000	8,879,000	21,682,000	19,000,000
Depreciation and amortization		382,000	330,000	746,000	654,000
Stock-based compensation		63,000	(9,000)	114,000	56,000
Operating income		2,864,000	1,526,000	6,618,000	3,855,000
Trading Cards and Autographs [Member] | Operating Segments [Member]
Net revenues		8,078,000	6,006,000	16,172,000	12,106,000
Depreciation and amortization		174,000	141,000	325,000	281,000
Stock-based compensation		27,000	6,000	44,000	10,000
Operating income		1,940,000	1,708,000	4,195,000	3,271,000
Other Segments [Member] | Operating Segments [Member]
Net revenues		678,000	819,000	1,812,000	2,093,000
Depreciation and amortization		84,000	96,000	176,000	245,000
Stock-based compensation		11,000	7,000	19,000	14,000
Operating income		$ 225,000	$ 331,000	$ 533,000	$ 674,000

[1] Includes service revenues of $2.4 million generated from outside the United States in the three months ended September 30, 2019 as compared to $1.7 million in the three months ended September 30, 2018.