Be aware...
a 4 pound duck is about enough for two people...
You can usually figure about 1/2 a duck Per Person (Pekin, or Long Island Duck)...
They are mostly breast meat, there's very little on the legs...
UNLESS you get a Muscovy Duck ... They have much larger breasts and legs...
But Pekin Ducks are mostly what you will find in the US...

I'm lucky, being from Eastern Long Island...
we have a few duck farms within a few miles... and we can get them fresh...
Otherwise, they will be frozen...
That may be one reason why you don't see them where you live...
They will be in the frozen food section... not on the poultry counter!