If the seller wont use a different freight system then I dont buy from them Geoff. simple as that.
If they dont advise me and use the GSP then stiff. they have ignored the person with the wallet after being alerted to an issue and get what they deserve. If i keep the part they get neutral/poor feedback. if I dont need it, I use the power of ebay and paypal and return the item as soon as im aware of the sellers actions. If the seller is out of pocket for being ignorant they need to own the problem.
Its no secret that ebays GSP is anything but accurate or cost effective and ebay dont appear to have changed a thing since its inception. The more people who protest the GSP the better the system will be for buyers and sellers. Who knows, just maybe Ebay could return to having a decent reputation for online sales.