Your case is different. In the auction you stated a shipping fee for US. In thread poster's auction in reference, it had shipping fees for different locations. For you it is not a binding contract unless you stated $x to Canada.The same thing is kinda happening to me. I was selling a bag to US people only and this girl asked if I would send it to Canada if she won and I said yes but she might have to pay more then my shipping price because I was not sure how much it would be. She agreed to this and I am just going to the post office to get an estimate and let her know and then I will ship it out after the okay and payment.