Note 10 - Stock-based Compensation - Summary of the Status of the Company's Stock Options (Details)	6 Months Ended
	Mar. 31, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($)
Outstanding (in shares) | shares	770,000
Outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 1.73
Outstanding, aggregate intrinsic value | $	$ 394,266	$ 352,700
Granted (in shares) | shares
Granted, weighted average exercise price (in dollars per share) | $ / shares
Exercised (in shares) | shares	110,000
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 1.57
Exercised, aggregate intrinsic value | $	$ 282,833
Expired (in shares) | shares
Expired, weighted average exercise price (in dollars per share) | $ / shares
Forfeited (in shares) | shares	(116,667)
Forfeited, weighted average exercise price (in dollars per share) | $ / shares	$ 1.31
Forfeited, aggregate intrinsic value | $	$ 130,667
Outstanding (in shares) | shares	543,333
Outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 1.85
Exercisable (in shares) | shares	410,001
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 1.98
Exercisable, aggregate intrinsic value | $	$ 265,334