It seems that the best way to stop people chargeing over the top postage charges is to report them to ebay for avoiding ebay charges for instance you see an item that is lets say .99pence on a buy it now but the postage charge is £19.00 but when you recieve it in post its only cost £1.75 you then get the idea that you have been ripped off, its now too late to complain and the seller has got away with it and avoided paying ebays listing fees. the best thing you can do is ask the seller the weight and check the postage yourself. if your getting ripped of tell the seller your reporting them to ebay if they do not reduce the cost then if they do not report them. or just keep getting ripped off.
help keep ebay honest