Plus, there can only be one. Its the kind of card you want so bad that if you manage to get it, you will consider your collection complete and may even stop collecting when you reach that point. Most of the time, when I see this term used here, it is loosely. As in it is used as "my current whale" instead of "the white whale" as in the story. I can see how this is in cards, perhaps, but I happen to have a "white whale" in my other collection. My other collection is Transformers, and while I am in a lull right now, my white whale (the item to end my collection forever) is the clear Lucky Draw Sixshot. There were only 10 made, in Japan and only 3 are in known collections.
Basically, I see the "whale" as being THE item that you want so bad you would trade everything you own for it, and once you get it, you won't be a collector in that field any longer.
