You might be asking the wrong guy on how to get poles across the border. I have a bit of a history with Canada Customs.
But seriously, there's a couple things to consider ...
If you live near the border and want to drive your new pole across, there is a certain duty paid on poles. It's not much ... maybe 15%, I forget ... so just pay it. Make sure you have a receipt for the pole to show at customs - even if it's a private purchase. Take my word for it ... crime doesn't pay.
If you want to have it shipped across the border, you'll need to clear it thru customs, so you need to designate a custom broker for that. It's just like shipping anything else across the border, except the size and shape is rather odd, so where it gets stored at your customs broker can be rather inconvenient. Thru an agent will be a few days slower, a bit more expensive and more inconvenient, so I recommend driving it across if you live close to the border. Also on the other side of the border, depending on how far away your pole is, you might want to get it shipped to a location close to the border - like a friend's place or a UPS storefront.
If I didn't answer your exact question, ask again, with more details. Like where you live, where in the states you plan to buy the pole, etc.
If you're thinking about buying a used pole, I don't think it's a very good idea to buy it sight unseen, in case it has nicks. By the time you get it shipped, it will be harder to negotiate or return it if you don't like it.
Kirk