If you are not looking to necessarily breed ducks but just want to raise some to butcher, you should look into ordering some White Appleyards from Holderread's. Apparently Silver Appleyards throw out some pure white ducklings every so often, naturally. I ordered some last spring that I need to butcher soon. They are pure white (so easy pickings), very large, calm but not fatty like Pekins. Lots of people raise Silver Appleyards for meat ducks, and these are genetically the same they are just white.
Ducks rule, chickens drool!