No duty - but you do have to pay 6% GST I believe.
No duty is paid on any merchandise you purchased from U.S. and many other countries nowadays (depends on where) due to various free trade agreements nowadays.
If you ship, try to ship via Canada Post (United States Postal Service) instead of UPS/FedEx -- they have the lowest customs processing fees (that's not duty -- it's a processing fee). These processing fees often exceed the GST that is collected, and is a source of contention for Canadians purchasing stuff from the US, but it is not duty. You can avoid most of these fees (and mainly just pay GST) by using Canada Post, or by driving down and purchasing.
That being said, sometimes things make it through Canada Post without any border processing (mind you, CCRA frowns on that.)