If a seller us using the GSP, often if you send the seller a message BEFORE bidding or buying, you can ask them if they are happy to send via USPS or Royal Mail as opposed to sending via GSP. More often that not, they are obliging. To bypass the GSP, you need to request an invoice from the shopping cart, so the seller can send a revised invoice with the adjusted shipping cost. Ordinarily, they can't send an invoice.