Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Condensed Consolidated Statements of Operations [Abstract]
Net revenue	$ 17,737,000	$ 19,339,000	$ 22,685,000	$ 26,203,000
Costs and expenses:
Production costs	13,411,000	15,273,000	17,942,000	21,414,000
Product engineering and development	454,000	556,000	902,000	1,095,000
Selling, general and administrative	1,984,000	2,523,000	3,943,000	4,320,000
Total operating expenses	15,849,000	18,352,000	22,787,000	26,829,000
Operating income (loss)	1,888,000	987,000	(102,000)	(626,000)
Other income (expenses):
Interest and dividend income, net of fees	553,000	553,000	1,243,000	1,123,000
Net realized and unrealized gains on marketable securities	1,269,000	2,611,000	743,000	4,838,000
Other		20,000	15,000	36,000
Other income (expense) total	1,822,000	3,184,000	2,001,000	5,997,000
Income before income tax expense (benefit)	3,710,000	4,171,000	1,899,000	5,371,000
Income tax expense (benefit)	733,000	1,405,000	(102,000)	1,730,000
Net Income	$ 2,977,000	$ 2,766,000	$ 2,001,000	$ 3,641,000
Basic Income per Common Share:
Net income per share	$ 0.31	$ 0.29	$ 0.21	$ 0.38
Diluted Income per Common Share:
Net income per share	$ 0.31	$ 0.29	$ 0.21	$ 0.38