For the website of an auction, it is preferable to add the tracking number when shipping. At that time, I will use the method of shipping to be able to track the parcel on international shipping. The cost is more than 25 dollars at least.
Due to the auction site system, it's better to add the tracking number at the moment of the shipment. Due to that, I would like to use the shipping method possible to trace for international shipments. That cost would be no less than 25 USD.