Note A - Summary of Significant Accounting Policies (Tables)
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12 Months Ended |
Sep. 30, 2017 |
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| Notes Tables |
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| Investments Classified by Contractual Maturity Date [Table Text Block] |
| | | September 30, 2017 | | September 30, 2016 | | Less than one year | | $ | 5,937,150 | | | $ | 5,527,075 | | | 1-5 years | | | 19,816,000 | | | | 10,703,000 | | | Total | | $ | 25,753,150 | | | $ | 16,230,075 | | |
| Allowance for Credit Losses on Financing Receivables [Table Text Block] |
| Year Ended | | Balance at Beginning of Year | | Additions Charged to Costs and Expenses | | Less Write-offs | | Balance at End of Year | | September 30, 2017 | | $ | 93,473 | | | $ | - | | | $ | (14,388 | ) | | $ | 79,085 | | | September 30, 2016 | | | 79,473 | | | | 25,000 | | | | (11,000 | ) | | | 93,473 | | | September 30, 2015 | | | 97,950 | | | | - | | | | (18,477 | ) | | | 79,473 | | |
| Schedule of Inventory, Current [Table Text Block] |
| | | September 30,
2017 | | September 30,
2016 | | | | | | | | Raw materials | | $ | 5,991,863 | | | $ | 5,702,762 | | | Work-in-process | | | 724,248 | | | | 471,305 | | | Finished goods | | | 1,737,456 | | | | 2,199,088 | | | Inventories | | $ | 8,453,567 | | | $ | 8,373,155 | | |
| Property, Plant and Equipment [Table Text Block] |
| | | September 30,
2017 | | September 30,
2016 | | | | | | | | Manufacturing Equipment | | $ | 5,370,962 | | | $ | 4,585,422 | | | Office Equipment | | | 3,600,006 | | | | 3,513,002 | | | Leasehold Improvements | | | 2,404,331 | | | | 2,422,669 | | | Vehicles | | | 193,702 | | | | 193,702 | | | Property, plant and equipment, gross | | | 11,569,001 | | | | 10,714,795 | | | Less accumulated depreciation | | | 6,134,829 | | | | 4,933,981 | | | Property, plant and equipment, net | | $ | 5,434,172 | | | $ | 5,780,814 | | |
| Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] |
| Year ended September 30, | | 2017 | | 2016 | | 2015 | | Net income | | $ | 3,847,839 | | | $ | 8,013,062 | | | $ | 4,682,008 | | | Weighted average common shares | | | 13,532,375 | | | | 13,372,579 | | | | 13,216,010 | | | Dilutive potential common shares | | | 128,431 | | | | 290,770 | | | | 371,522 | | | Weighted average dilutive common shares outstanding | | | 13,660,806 | | | | 13,663,349 | | | | 13,587,532 | | | Earnings per share: | | | | | | | | | | | | | | Basic | | $ | 0.28 | | | $ | 0.60 | | | $ | 0.35 | | | Diluted | | $ | 0.28 | | | $ | 0.59 | | | $ | 0.34 | | |
| Useful Lives [Member] |
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| Notes Tables |
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| Property, Plant and Equipment [Table Text Block] |
| | | Years | | Equipment | | 3 | - | 7 | | Leasehold improvements | | 7 | - | 10 or life of lease | | Vehicles | | | 3 | | |