The cost of shipping (actual transport) is not related to the value of the item. It costs $12 to ship a $10 vintage paperback from Ontario to Alberta, for example.
Duty is not charged on US -made items (or Mexican or Chilean, which also are signatories to NAFTA), but it may be on items purchased in the USA but manufactured elsewhere.
Sales tax (between 5% and 15% depending on your province) will be charged. Even if the item is used.
There will be a fee from the carrier. PitneyBowes seems to charge around $5. Canada Post $10. Other couriers charge from $20 up depending on the value of the shipment.
CBSA/Canada Post have been missing an important income stream by ignoring small and lower value imports. Of course, this may be because it costs too much to process the fees. Why pay $20 to collect $5?
The answer would be to raise the limit to $200 (which cross-border shoppers enjoy) and actually charge the duty and tax. Write your MP. His House of Commons postal code is K0A 1A6 and you don't even have to stamp the envelope.