Just have the buyer send the additional $ in paypal after the fact. I've done this numerous times when international buyers have paid for something but have not actually paid for the international shipping fees (only domestic ones). What they need to implement is the ability to include a domestic and international shipping fee in the listing and it pops up the option for the buyer before they actually purchase. So there's no "forgetting" about it when purchasing.
4/22/16 at 7:46pm