Hi

I have listed an item that has already received a few bids and as I was looking at it earlier, I realised that I have somehow chosen an expensive option for postage.  I only intended on charging $15 for postage, but it states over $30 on my listing? I've obviously done something wrong, but I want to change postage cost as a) it will turn of potential buyers and b) I don't want to have to pay additional fees, as I understand that the new ebay changes mean that you get charged fees based on auction price + postage? On that note, if a buyer decides to pick up item instead of me posting the item, does that mean you don't get charged the fees on the postage? 

thanks