Add a international shipping disclaimer regarding possible additional costs

This is the second time I have had this issue: I sold one game to a buyer from Canada, the shipping being $17.27 for a $35 game. That ate considerably into my profit. That issue aside, I just today sold another game to another buyer in Canada for $50. For the first game, maybe it was a mistake on my end in as how I had shipped it but the receiver ended up paying an additional $65 at his local post office. In this particular sale, I advised the buyer I will not have the control over tarriffs and receiving costs if he is to be charged additionally. I promptly offered a refund since I knew he would not accept POSSIBLY paying more than what was advertised. Even though I lost a sale, I would rather keep a potential customer over the profit. That being said, the disclaimer that international shipping costs of an additional $10 covered under the original selling cost does not sound fair on my end without a better disclosure since even if the stated $10 shipping cost cuts into my profit. That being said, the shipping disclaimer should be adjusted to maybe state "International shipping would be extra" and provide either an option to communicate this to the buyer before the actual sale so that the correct amount is displayed. Example $50 for the sale, $17.27 for the additional shipping AND advising there is a potentional charge at their local post office if they want to keep the item and advise this is on them at this point and no longer on the seller. Otherwise, put a disclaimer that unless they accept the possible additional fees, then the item would be refunded at their cost (Paypal charges $2.50 for a refund).