I just use chicken starter and later - layer. Not alot of brand choices at the stores down here.
I think there's a feed more tailored for ducks, but I'm not paying a premium for it. Just stick with chick feed and crush up some niacin in their water/food while they're growing.
I ended up getting Nutrena meat bird food. It was recommended for ducks up till laying age. It was cheaper than the DuMor and Purina and I liked the ingredient list on this better as well. I have their brooder and everything set up and ready to go- the duckies should be here by Friday!