Note 10 - Leases (Details Textual)	3 Months Ended		9 Months Ended
	Jun. 30, 2021 USD ($) ft²	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) ft²	Jun. 30, 2020 USD ($)	Oct. 09, 2020 ft²	Feb. 12, 2020 ft²	Aug. 01, 2017	Jan. 01, 2015
Operating Lease, Weighted Average Remaining Lease Term (Year)	3 years 1 month 2 days	4 years 2 months 15 days	3 years 1 month 2 days	4 years 2 months 15 days
Operating Lease, Weighted Average Discount Rate, Percent	3.41%	3.48%	3.41%	3.48%
Operating Lease, Payments | $	$ 242,736	$ 237,726	$ 722,537	$ 574,381
7050 Winnetka Avenue North, Brooklyn Park, Minnesota [Member]
Area of Real Estate Property (Square Foot)	85,000		85,000
Lessee, Operating Lease, Term of Contract (Year)								10 years 2 months 1 day
Operating Lease Termination Fee | $			$ 249,000
Tijuana, Mexico [Member]
Area of Real Estate Property (Square Foot)					46,000
Lessee, Operating Lease, Term of Contract (Year)					3 years		3 years
Tijuana, Mexico 2 [Member]
Area of Real Estate Property (Square Foot)						52,000
Lessee, Operating Lease, Term of Contract (Year)						42 months
Lessee, Operating Lease, Number of Options to Renew						2
Lessee, Operating Lease, Renewal Term (Year)						3 years