The way I understand it, and I was wrong once before (but it was it was the others guys fault
) ...
There are no 'duites' for items that cross the US / Canadian border.
GST (5% Tax) is due on pretty much everthing ....
Depending on the carrier , you can pay administrations fees or Brokerage Fees the formula for how this is calculated is a mystery to me but I am sure it is based on the phase the moons , some dice and the mood of the individual processing the package.
The truest sentiment here is it really is a crap shoot. Personally
I have received a $250 item from the US delivered by UPS and paid $60.00 'Brokerage Fees'. I have always paid Brokerage Fees with UPS.
Fed-Ex I usually pay a Brokerage Fee
USPS - occasionaly I pay an 'Administration Fee' of $10.00 (regardless of what value the item is).
Other times I have paid nothing .... so if you like craps, roll the dice , but if time is not of the essence I will always use USPS given the choice.
YMMV...........Dave