Most ducks cost between $10.00 to $20.00 each as ducklings.
If you buy the duckling or duck from someone local it will usually be cheaper than buying a duck from a farm store.
Sometimes you can buy a full grown duck from a local farmer or person who breeds and raises ducks for $10.00 to $20.00
I've seen ducklings for sale at feed stores sometimes for $10.00 each.
Just make sure you have enough room for the duckling or duck once they are full grown and it's best to have at least 1 acre of land for the duck.
Ducks need room to roam around outside to be happy and healthy as they do not make good house pets.