It might be worth getting them from the feed store, if they will be getting the ones you want. I didn't check where you were located, but after 3 or 4 weeks you will desperately want to get the ducklings outdoors in a pen, rather than indoors in a brooder, so make sure the weather will have warmed by then or that you have a heat lamp for them.
I think Pekin is maybe what you are thinking, but I don't know how docile or pet-like any ducks are. In my experience they can be docile at times, but drakes can potentially be unruly and ducks (females) become somewhat stand-offish as they mature. If you spend a lot of time with them, you will increase your chances of having a more pet-like duck. Also I hear having just one duck will result in the same, but I don't think that is very fair for the duck.
A few people here have said they really enjoy the temperament of muscovy ducks (females anyway).