Hell, after looking at the web, the only place I could find that sold ducks foot was Seedboutique, and they don't even have it in their list anymore. There was one guy who was working with them, went by Wallyduck. Seedboutique still sells his seeds, so you might be able to send them an email and see if they can still get the ducks foot from him. Maybe they'll do a special order for you?
One thing, I have no experience with seedboutique, so you might want to look through the forums and see what you can find out about them. I've only ordered seeds once, and that was from attitude.