The money an importer pays on things they bring into Canada are:
Duty-- charged by the federal government.
Taxes- charged by provincial and federal government
Service fee- charged by the shipping company
There is nothing there charged by the seller.
Now-- with the Global Shipping Program, Pitney Bowes who run the program collect appropriate duty and tax and charge the buyer a service fee. This is paid along with the seller's shipping fee (which only carries the purchase to the GSP plant in Kentucky) at the time of purchase.
The seller who does not use GSP could ship with a courier like UPS. The courier will collect the applicable duty and tax and their service fee on the buyer's doorstep.
The seller can also ship with the USPS First Class International service, which transfers the parcel to Canada Post. CP and the Canadian Border Services Agency usually ignore parcels valued under $100. although technically and legally they could levy the duty, sales tax and a service fee.
You are asking the seller the impossible.