With NAFTA in place you shouldn't have to.
There is a tax for US goods being shipped to Canada. I too thought NAFTA (North American "Fee" Trade Agreement) was supposed to do away with that. I shipped a pair of Magnepan MGIII speakers to a buyer in Toronto, and he not only had to pay duty, tax; he also had to hire a "broker" to shepard the speakers through customs. Speakers took three days to get there and over two weeks to clear customs, all at considerable expense to the buyer. I can't imagine Uncle Sammy not wanting a piece of the action for goods comin the other way, so do your homework before committing...
My understanding is TO CANADA is possibly a fee, maybe a big % plus perhaps hassles as mentioned before. Ditto to EU.
but fron Canada to the USA, nothing. only a declairation of value, and they may want to open the box to inspect.
This is my impression, and is not a guarantee. Same from EU to USA, no problem.
When I brought a pair of used ProAc speakers, made in England, from Canada into the U.S., customs on the U.S. side tacked on a 10% duty. They looked at the bill of sale from the previous owner to determine the value and then spent quite a while looking through a phone-book sized list of products to figure out how to categorize the speakers.
They didn't really seem to have a clue what they were doing but I wasn't in the mood to hassle them since it was late in the day, I still had a couple of hours driving to go, and I'd gotten a great deal on the speakers, in the first place.
I helped a friend buy a used pair of Linn Ninkas that were shipped here from Canada and she got a bill months later from U.S. Customs for the duty, this time for 5%.
I bought a CD player from Canada and it arrived with no mention of duty at all.
When I was negotiating recently with someone in Canada who wanted to buy some electronics I was selling, I asked him to check about the duty going his direction and he was told it would be 15% (which killed the deal.) All the gear in question was made in the U.S.
So, yes, you'll probably have to pay duty, maybe, but will probably have no clear idea what it's going to be until you actually do it. The application of the regulations seems to be completely haphazard.