Hello 'jessica',
It's not a shipping charge, it's a combination of our dear government wanting a chunk of every nickel we spend (well, every $20) and Canada Post's fee for processing the paperwork.
Any item over $20 in value is subject to duty and taxes. As you know, tax is on just about everything, but duty on some items like clothing can be especially high (18%) depending where it's made, - something to think about when you're contemplating that designer handbag from Italy.
Have a look at the following link about importing items through the mail:
http://www.cbsa-asfc.gc.ca/import/postal-postale/duty-droits-eng.html
Every country has a different 'import limit', - in Canada it's 20 bucks. As such, if you look again at the listing it should say somewhere near the bottom that 'import charges are the responsibility of the buyer, yada-yada'.
Most things arriving through the mail are not assessed, simply because the Canada Post is understaffed and overworked so they cannot chase down every cent. Items coming by courier will always be assessed and often with a hefty brokerage fee as well.
Any time you buy from outside Canada, it is wise to figure out in advance what the possible charges could be, and if your parcel is assessed be prepared to pay it promptly and graciously.
