A family friend of ours breeds wild ducks, turkeys, phesants, and quail.

If I were you, I would not buy a duck through a pet store. Look around your area and see if their are any breeders. Most likely there is. They don't charge much at all, and they are in a better situation than pet store ducks, and their health most likely will be better.

i heard it is better to have two ducklings then one.....because they keep each other company. is this true?
Yes. It's true. Since ducks are so cheap to buy, you could even get like a mini flock of four or so. That's what I personally would do.