Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operations:
Net income	$ 8,791,000	$ 7,397,000
Adjustments to reconcile net income to cash flows provided by operating activities:
Purchases of marketable securities	(188,082,000)	(413,993,000)
Proceeds from sale and maturity of marketable securities	186,812,000	413,491,000
Change in fair value of marketable securities	1,256,000	(692,000)
Deferred income taxes	(1,082,000)	6,000
Depreciation and amortization	1,010,000	862,000
Provision for doubtful accounts	80,000	65,000
Stock-based compensation	53,000	54,000
Loss on sale of fixed assets	3,000
Changes in assets and liabilities:
Accounts receivable	(495,000)	(338,000)
Costs and estimated earnings in excess of billings	(1,568,000)	24,000
Inventories	443,000	(3,687,000)
Prepaid expenses and other current assets	705,000	(109,000)
Accounts payable	1,773,000	803,000
Customer deposits	(4,883,000)	2,740,000
Accrued expenses and other current liabilities	98,000	1,095,000
Total adjustments	(3,877,000)	321,000
Cash flows provided by operating activities	4,914,000	7,718,000
Cash flows used in investing activities:
Capital expenditures	(3,317,000)	(854,000)
Cash flows used in investing activities	(3,317,000)	(854,000)
Cash flows from financing activities:
Proceeds from stock option exercises	381,000	136,000
Cash flows provided by financing activities	381,000	136,000
Net increase in cash	1,978,000	7,000,000
Cash at:
Beginning of period	22,933,000	18,219,000
End of period	$ 24,911,000	$ 25,219,000