Oh I had a shocker trying to send a defective USC back Canada a a few years ago. I went to ship it back to Canada when US Office wanted over $90 one way to send it. As Bert suggests on sending emails works as I contacted the vendor on the Canadian side and they sent me round trip label for $35. I could brought another unit for what the USPS wanted to send it round trip. It is same when I try to ship anything here even within the US borders. The local USPS tries to eat me alive on charges yet I have vendors shipping for little. Because the local charges I simply gave up shipping anything out.
Then of course there is the nightmare of trying to get anything delivered by USPS too. I currently got a package currently stuck in the Boca Raton, FL post office since June 4. Package received, awaiting acceptance status on the tracking. What worst is I already had three packages lost by the USPS this year. Since I depend on my deliveries I refuse to them unless there is no other option.
I also know a couple members that have their own US post box where they ship part to it and just drive across the border to pick them up but the OP may to far out to do this.