(WSJ) - Type the words "empty wine bottles" into eBay's search engine and you will soon be presented with a number of options to purchase all manner of empties from the world's greatest wine estates. Within seconds, I found examples of magnums and bottles of distinguished vintages from Bordeaux and California. I can understand keeping a bottle as a trophy from a particularly special vintage or grower, but I have no inclination to start a collection of empties. So why would somebody want to buy an empty bottle, in some cases for hundreds of pounds?