OK, this in some ways is a bit ambiguous, but it's the best I can do, given the complexity of the topic...
Our latest go-round with UPS landed us a deal that reduces our brokerage-fees by 60%-80%, depending upon the value of the order (it's tiered). So basically, it's an ENORMOUS cut that should greatly reduce your landed cost. The savings are already effective.
We do our best to ship USPS when we can, which eliminates some of these expenses, but USPS is a mixed-bag, because the size/weight limitations are more restrictive, and on heavier orders, USPS is often more-expensive than UPS. Not to mention USPS isn't as reliable and quick as UPS. So it's a bit of a monkey puzzle.
Online, due to the complexities of orders (i.e. you can't put a hood molding in the same box with a brake drum, and you can't hope to write a computer program that takes into account all the various "what-if's" of packing/shipping an order such that everything arrives unscathed), we are forced to simply look at our overall expenses into Canada, versus our overall revenues from Canadian orders (shipping charges), and come up with a flat-rate percentage to charge. That rate online is currently 20%. And currently, we're actually losing money on shipping with the 20% rate, but that's where it's sitting for now. I know that other companies like Summit are more sophisticated in calculating shipping to Canada, but we're not a behemoth like Summit..
If you CALL your order in (Michigan is usually the logical place to call, unless you're in BC or Alberta, in which case California should be your target), we have the latitude of determining best-carrier (balancing cost/speed/size) and bill you "actual cost", which may sometimes be cheaper than our 20% rate, but sometimes may be more. It depends on the contents of the order, and how it needs to be packed.
That's the best I we can do with it. No business can afford to ship at a considerable-loss ongoing, without either adjusting/changing their fee structure, or by simply HIDING the costs of shipping by inflating the costs of the merchandise (burying shipping expense into the prices of parts). Long story short, we don't do that...