In my 'Add to Cart' buttons, I ask PayPal to calculate shipping costs based on product weight and the area code I am shipping from. However, when I go to print out the shipping label, the costs are consistently higher than what PayPal charges my customer. On domestic shipments I may only be in the hole $1-$3. However, on international shipments the difference is $5+. Not huge on each sale, however, when I am shipping hundreds of my books, this really adds up!
