I just ordered a BMW fairing and windshield from Poland. The fairing was $600 less than ordering from Wunderlich in the U.S. The package cost 80 Euros to ship and arrived at my door with no fees.
I use Cross Border Pick-ups to bring packages from the U.S. and I declare them as vintage parts "Parts Exempt Under Canadian Tariff 9966.00" and they arrive with no duties if they are for a vehicle older than 25 years.
Also look here:
https://www.cbsa-asfc.gc.ca/publications/dm-md/d10/d10-15-20-eng.html
In general, if you use a courier service, you will be charged duty, taxes and brokerage fees. If you use mail from the U.S, you will be charged taxes and very rarely duty. If the package comes via mail from somewhere with non-English writing i.e. Poland or Thailand, it will arrive with no fees or taxes.
That's my experience anyway.
Cheers