Note 11 - Stock-based Compensation - Outstanding and Exercisable Stock Options (Details)	12 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Stock Options Outstanding (in shares)	770,000
Exercisable Stock Options Outstanding (in shares)	443,334
Aggregate Intrinsic Value | $	$ 352,700	[1]
Exercise Price Range 1 [Member]
Exercise Price (in dollars per share) | $ / shares	$ 1.31
Stock Options Outstanding (in shares)	150,000
Exercisable Stock Options Outstanding (in shares)
Remaining Contractual Life (Year)	9 years 182 days
Aggregate Intrinsic Value | $	$ 103,500	[1]
Exercise Price Range 2 [Member]
Exercise Price (in dollars per share) | $ / shares	$ 1.28
Stock Options Outstanding (in shares)	130,000
Exercisable Stock Options Outstanding (in shares)
Remaining Contractual Life (Year)	9 years 109 days
Aggregate Intrinsic Value | $	$ 93,600	[1]
Exercise Price Range 3 [Member]
Exercise Price (in dollars per share) | $ / shares	$ 1.36
Stock Options Outstanding (in shares)	200,000
Exercisable Stock Options Outstanding (in shares)	200,000
Remaining Contractual Life (Year)	9 years
Aggregate Intrinsic Value | $	$ 128,000	[1]
Exercise Price Range 4 [Member]
Exercise Price (in dollars per share) | $ / shares	$ 1.79
Stock Options Outstanding (in shares)	50,000
Exercisable Stock Options Outstanding (in shares)	33,334
Remaining Contractual Life (Year)	7 years 219 days
Aggregate Intrinsic Value | $	$ 10,500	[1]
Exercise Price Range 5 [Member]
Exercise Price (in dollars per share) | $ / shares	$ 1.81
Stock Options Outstanding (in shares)	90,000
Exercisable Stock Options Outstanding (in shares)	60,000
Remaining Contractual Life (Year)	7 years 146 days
Aggregate Intrinsic Value | $	$ 17,100	[1]
Exercise Price Range 6 [Member]
Exercise Price (in dollars per share) | $ / shares	$ 3.21
Stock Options Outstanding (in shares)	100,000
Exercisable Stock Options Outstanding (in shares)	100,000
Remaining Contractual Life (Year)	4 years 182 days
Aggregate Intrinsic Value | $		[1]
Exercise Price Range 7 [Member]
Exercise Price (in dollars per share) | $ / shares	$ 2.45
Stock Options Outstanding (in shares)	50,000
Exercisable Stock Options Outstanding (in shares)	50,000
Remaining Contractual Life (Year)	2 years 182 days
Aggregate Intrinsic Value | $		[1]

[1] For stock options outstanding.