Hey, peeps,
For anybody who is raising larger batches of birds than can easily be hand-plucked or who hunt a lot and arrange to take full carcasses and give back the breasts, this link might interest you:
http://achornfarm.blogspot.com/2009/06/how-to-build-chicken-plucker_30.html
This link is not for vegetarians or people who see picking something up from the grocery as fine but are hurt by the idea of taking an animal from the stages of living through to the plate.

This is listed as $200-400. It cost about $350 USD locally a year ago (buddy made it; estimated $500-600 around here if buying all parts).
It takes about 20 seconds to a minute per bird.

This machine is not fab-o for turkeys (best guesses: they're too big) and is 50-50 with extra large domestic ducks (likely size) or runner-type ducks (possibly too streamlined).
It does a decent job for medium domestic dabber body types and geese under about 10-12 pounds, although you have to finish up for it, plucking odd broken or remaining feathers.
You have to stop it and pull feathers out for any 6+# waterfowl and the turkeys.

It will not work for diver ducks AT ALL. Almost every single quill will break off for diver ducks before they come out and you can't keep them cool enough. Now, ducks with yellow fat don't have worthwhile skin as it is and divers are mostly going to have yellow fat, so that may be a nonissue.

This is not great for small birds like dove. It will help you some, but you still end up plucking.

Just thought somebody spending $$$ or days might be interested. Cheers!