The only time I don't charge postage is if people collect the item from me - as is said, the postage fee is part of the deal.
mrs O - If I was charging £4 for postage for a top, it would have to be for recorded delivery etc - I tend to overestimate postage and packing (don't forget you can include packaging, getting to the PO, etc. in your charge), then if the price is quite a lot less than I'd estimated, I give them a partial refund. I couldn't do it any other way.
grasscarp - if you HAD posted the item, you wouldn't have know if this person looked hard up or not - but no, you spent the postage money on petrol. My sales this weekend are waiting til the PO opens again on Tuesday!