Hey shelly! I had a problem only this week, Im after a J Crew necklace and there were 2 exactly the same on E-Bay, one seller wanted $15.95 international post, and the other wanted $28.99 US. When I asked if the higher one would match the lower post price, he said postage was not determined by him, he simply put his item details in, and the E Bay site selected the postage required and it included registering and insurance of the parcel. Personally I think its crock! If one person can ship an item for a certain price, the next person should be able to ship the same item for the same price. Look out for anything from the US, there post is totally unreasonable. I collect animation cels, which are just posted in an envelope (business size), 

the US charge $40 plus, and the UK only charge $7.99 AUD.