Hello,
I very rarely sell anything on ebay but have started listing things every now and again. I am rubbish with postage costs and last week charged £2 to post an item that cost £4 to send. So I listed something else with £4 p&p and it only cost £2.
As a buyer I just suck it up if I over pay postage, but does it annoy you? I don't know if I should refund the £2 to the buyer.