It really has nothing to do with time-of-transit. One needs special certification permits to ship overseas (and to HI). Also, shipping internationally is very expensive. I recently had a Canadian lady who wanted to purchase some of my cork slabs. She even paid for them up-front. I would not need a permit to ship cork to Canada but I warned her that shipping might be ridiculous. Shipping to the West Coast and Alaska might cost $15-$20 for 10 lb. box. I found out that the same box shipped to Canada was going to cost approximately $50! I refunded her money.
