Condensed Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net income	$ 4,243,623	$ 2,678,429
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	1,824,517	1,613,394
Change in allowance for doubtful accounts	0	210,000
Amortization of discount on investments	(64,327)	(43,601)
Stock-based compensation	541,884	1,535,628
Changes in operating assets and liabilities:
Accounts receivable, net	18,912	3,308,314
Inventories, net	(5,868,972)	625,873
Other assets	190,796	(116,872)
Accounts payable, accrued expenses and deferred rent	1,553,798	(901,754)
Net cash provided by operating activities	2,440,231	8,909,411
Cash flows from investing activities
Purchases of property, plant and equipment and intangible assets	(1,493,341)	(1,099,089)
Purchases of investments	(31,837,930)	(17,444,393)
Proceeds from maturities of investments	30,163,000	7,235,000
Net cash used in investing activities	(3,168,271)	(11,308,482)
Cash flows from financing activities
Proceeds from issuance of common stock under employee stock purchase plan	348,776	313,891
Proceeds from issuance of common stock upon exercise of stock options	10,968	24
Tax withholding related to vesting of restricted stock grants	(5,803)	(431,779)
Repurchase of common stock	(428,654)	0
Net cash used in financing activities	(74,713)	(117,864)
Decrease in cash and cash equivalents	(802,753)	(2,516,935)
Cash and cash equivalents, beginning of period	10,081,721	8,547,777
Cash and cash equivalents, end of period	9,278,968	6,030,842
Supplemental disclosures for cash flow information
Cash paid during the year for income taxes	469,529	1,081,068
Non-cash financing activities
Cashless exercise of stock options	$ 10,962	$ 17,390