I'm not sure you'd be able to sell them legally anyway, could you? Have you got the required hygiene certificates? I find the gutting easier than the neat plucking - the hardest thing with ducks is definitely getting all the feathers out - so I think you'd be better off learning to gut than trying to find buyers for ungutted ducks. The biggest problem is that the body cavity is smaller than poultry (or at least in the breeds I keep which are all big) so it's harder to get your hand in.