I got my 2 Khaki Campbell girls from a local 4-H family at the end of the summer - the kids were done with the project, got their ribbons, and didn't want the poor ducks anymore! You could check with your local 4-H troop and see if anyone has any - mine were free, they were glad to be rid of them.
Mine had been left loose on the farm from the time the county fair was over until I got them, and had become very distrustful. This is the second year I've had them, and now they've completely warmed up to my whole family. They run towards us and beg for treats when we go outside! They can differentiate between a family member and a stranger, and get quiet and leery if there's someone they don't know in the yard.
Mine each lay an egg almost every day from the end of March through late October, and supply almost all the eggs my family needs (we're expanding the flock with some Dark Campbells this spring - actually, they're arriving later this week!) - so, by all means, get some Campbells!
