If you are the one shipping to Canada, you don't have to worry about what happens at the border, it is the one receiving the package that will have to pay for brokerage fees at the border. If you are the one paying for shipping, then you will pay the international shipping rate for the item. I think brokerage fees (border fees) only apply if the value of the item exceeds $200 (Canadian currency) and the receiver has to pay this amount before the item can be signed over to him/her. So if the item is valued at less than 200, then there shouldn't be any extra costs other than shipping.
As for taxes, as far as I know if the person you are shipping it to is paying you for the item, he/she will pay tax on top of the selling amount. Canadians get the end of a really sh**ty stick when they buy from the U.S. A set of headlights I got off ebay were listed for 68.99 USD and when it was all said and done, it cost me about $200 CDN.
This has been my experience, someone correct me if I'm wrong on any of this.