Consolidated Statements of Operations - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Net revenue	$ 105,075,000	$ 103,479,000
Cost of goods sold	76,038,000	82,935,000
Gross profit	29,037,000	20,544,000
Operating expenses:
Product engineering and development	3,458,000	4,325,000
Selling, general and administrative	12,154,000	12,052,000
Total operating expenses	15,612,000	16,377,000
Operating income	13,425,000	4,167,000
Other income (expense), net:
Interest and dividend income, net of fees	2,108,000	1,305,000
Realized and unrealized gains (losses) on marketable securities, net	3,243,000	(7,009,000)
Other	0	(156,000)
Other income (expense),net	5,351,000	(5,860,000)
Income (loss) before income tax expense (benefit)	18,776,000	(1,693,000)
Income tax expense (benefit)	4,110,000	(1,321,000)
Net income (loss)	$ 14,666,000	$ (372,000)
Basic earnings (loss) per common share	$ 1	$ (0.03)
Basic earnings (loss) per common share	$ 1	$ (0.03)