UPS, Fedex (and I'm guessing any other courier company) is going to charge you a "brokerage fee". which essentially is to cover the cost to do "paperwork" to import your time over. It's based off the value of your item to a certain extent. USPS for some way doesn't charge the brokerage fee, since I'm guessing because you fill in the customs declaration form when you mail it.
However, GST and PST will probably be applied to it (varies from province to province), and depending on the item it might be subject to duties (it depends on where the item is made).
The Gift under $25 is a good way to get around it. It's going to be tough to get a tracking number for the item through USPS. I think they can do DC for you, for a fee. If you live near a border town, have you considered driving over to Canada and mailing it instead? You'll be hard pressed to send the item with tracking for under $15.