Although I dont order any fishing tackle from US, over the past year or so I have ordered lots of accessories for my Polaris Ranger.
I agree with USPS being the best way to go, however some companies will only ship to Canada via UPS...you need to ask what carrier they are using.
Even if they do use UPS, you CAN call UPS directly and find out the brokerage, customs and duty costs that will be on top of the purchase price and the current exchange rate. Then you can do the math to see if you are saving any $.
Generally the brokerage costs get large when it is heavy or has a high value...
Even with UPS I always seem to come out ahead then trying to source the same item here in Canada. Fishing tackle IMO is not so bad....you can find most items in US in Canada or have a store order them in for you, (they are typically already set up to reduce broker fees.
My issue with UTV accessories is that the aftermarket manufacturers are way ahead of Canadian companies...so if you want something, the US is the only place to get it....so far I have been very satisfied with my purchases, and have saved a lot of money over buying Polaris accessories from my dealer.
2 cents
M.