When selling, I like to include the shipping cost in the asking price. I usually have a pretty good idea of the cost to ship. Sometimes though, I am a little low, and take a loss on the shipping. Very rarely, I am a little high, so it averages out. If I come up with a sale where I find the estimated shipping was way too high, I will offer send the buyer a refund for any overcharge. I almost always have the shipping a little underpriced. But hey, so I lose a little, I am not in this hobby to make a profit.