Please try to find one that has breeds you like that are geographically the closest as well. I bought from a hatchery a long ways away and it was too stressful on the birds because the post office takes so long. Several died I believe because it was too much traveling.
The closest place i can think of is Ideal poultry http://www.idealpoultry.com/assortment.html
Their prices are pretty low so I very strongly suggest buying sexed ducks. the Mallards and rouens are available now and the khakis will be in may. If you're also planing on buying a drake i'd suggested getting a khaki or mallard drake if you're getting all 3 breeds. A rouen drake can definitely hurt a mallard hen during breeding season.
I agree with everyone else in this thread, hardly any hatcheries have Muscovy ducks. their eggs are hard to incubate, and they have low hatch rates, unless set under a broody Muscovy. Also, Muscovies hardly give any eggs, a good hen in my climate gives me 90 a year. And it is near impossible to keep large scale breeding flocks of muscovies because the hens would constantly be going broody. The Muscovy is a struggle for hatcheries!
I love Moscovies, I get mine from local breeders, swap meets, and poultry shows.