It does not matter if one purchases or imports new or used items. The rules are the same and the level of taxes is the same (plus $9.95 handling charge to Canada Post).
From the official Government of Canada website: http://www.cbsa-asfc.gc.ca/import/postal-postale/duty-droits-eng.html
In Canada if you go to your used car dealer, you will be charged HST or GST although the tax had been charged previously to the first buyer. On a smaller scale if you go to Value Village and purchase a used pair of used or shirt or dress or whatever, applicable tax (GST or HST) will be charged.
You are looking at an item coming from an American seller enrolled into Global Shipping Service (GSP).
The "import charge" is an amount charged by Pitney Bowes, working under contract for eBay, to arrange for consolidation of shipments from their distribution centre in Kentucky to your location in Canada.
For items priced at more than Cdn$ 20.00, the "shipping charge" shown will include the amount due to the seller to ship domestically from his location to Kentucky and the amount to move the parcel from Kentucky to your destination.
The amount shown under "import charges" represent the amount of GST or HST payable plus a handling fee ($4/$5) to Pitney Bowes plus duty (if applicable). Unfortunately, many sellers do not properly inform eBay at time of listing on where the item was manufactured. We all know it is duty free if manufactured in the USA or Mexico under NAFTA (although GST or HST apply). If the seller does not show the item manufactured in NAFTA country, duty will be calculated automatically and included in "import charge".
For items priced at less than $20, there is no "import charge". However, in such instance, the shipping charge will include both shipping charge and the handling fee from Pitney Bowes ($4/$5).
Most Canadians buyers do NOT buy listings offered by American sellers requesting shipping through GSP.
By the way, it does not matter under Canadian laws if the item is new or used. Both require payment of taxes (GST or HST) and duty if applicable.
Show with popcorn? 
There is no point ..... Obviously the poster has his mind made up and does not want to learn. There is nothing anyone can do for him.
Now, for readers really and seriously interested in learning about NAFTA, here is the full text of the Agreement:
http://www.sice.oas.org/trade/nafta/naftatce.asp
Happy reading
My understanding is that seller needs to end the listing with GSP and start a new listing (using "sell a similar item) shipping with USPS.
Your seller can look here at "Alternative shipping options", re Canada, and "Opting out"
www.pages.ebay.com/help/sell/shipping-globally.html#opt-out
Also, the FAQ, good luck.
