When I bought my MSR Carbon Reflex 2 I got charged 30% tariff for tents not made in the USA, plus the regular 13% HST plus the $5 fee the government charges me for the hassle they go through to charge me the other fees.....plus the seller was an idiot and he listed the value at $500 even though I clearly communicated with him to list the value at the actual purchase price of ~$350.
My bill was about $200 in taxes, fees and tariffs. Thankfully it wasn't sent via UPS or they would have added another $100 in brokerage fees on top of that. I was able to recover about 1/3 of that $200 when I submitting documentation showing the tent was only bought for $350, not $500. Even still, it would have been cheaper to just buy it for full price at MEC.
In general, it seems that most of the people at the border don't know about, or don't enforce these tarrifs. The Carbon Reflex 2 was the only time I've been stung on tarrifs. I rightfully wasn't charged tarrifs on the Echo I because it's made in the USA. I don't think I was even charged the 13% HST. Sometimes the border guys just don't bother. Back in Ontario I got charged HST + handling fees on anything worth over $20 as per the law, but out in BC a lot of the time they don't bother if it's under $100 or so.
When I bought my REI Quarterdome T2 (made in Asia) I didn't get charged any tent tariff.