After years of working in the retail trade, I would suggest that all customers receive the same fair treatment when it comes to postage and packing.
Remember it is not the customer's fault that they have been fortunate to win something at a very low price. Occasionally one will sell something at 99p when it clearly cost you more and you were hoping to receive a much higher bid.
I believe that one should still offer the same fair service to that person. Take the same care in packing and post promptly.
You will feel that you have given someone a little treat, and furthermore they are likely to return for other goods.
We all hope to be lucky sometime. Be generous with your heart and hopefully you will receive the same kind of luck one day. Such is the joy of ebay!