Always pays to get the SKU of the item and do a search in Canada. I have found times when I could buy the item at the US price with no exchange involved. Sometimes Cdn shipping is a tipping point as to who is cheaper. Brownell's is pretty good as to shipping prices, I use "ocean freight " for shipping and let them pick the cheapest shipping. The bulk of the time it comes in tax free. Just had 15doz decoy heads , made in China, ordered in the US, dropped at my door, no sig, no taxes, no S&H chg. Had 8 boxes of decoys from US, made in China, S&H chgs, paid duty on one box, tax on 4, 3 were del'd to house no chg of any kind. Recently bought 3 dies out of US, no taxes, probably 20.00 overall, cheaper than advertised up here, because the US freight factor was cheaper than up here. And I've bought stuff I couldn't get right away up here, that was more expensive to get from down south, but, wasn't willing to wait for. Usually, that doesn't work out to be too much more, 10-15.00.
Do some research, take your chances and roll the dice on the gst and duty if it may be applicable, watch for US vendor S&H charges, use USPS, not UPS.