So I sold a bag on eBay to a buyer in the UK. He/she paid $750 plus shipping. Insurance here goes in $100 incriments, so I can not insure the bag for $750, it has to be $700 or $800. Naturally, I insure the bag for the greater value so all of the money he/she paid is covered. I just received a message from he/she saying that they are angry I insured the bag for $50 more than he/she paid, and they want me to pay $100 to help cover customs! What are my rights here? If I refuse to pay can they return the bag even though I said all sales are final?