I don't remember all the ins and outs of the docking issue, but I thougt that only the breeder can make this decision and that the pups had to be docked by a vet within a few days of being born. I'm sure they have to claim that the dogs are working, hence if you are buying from a show breeder then they won't do this. You would have to find a breeder who breeds dogs for the working market I'd imagine.
Sounds like it is out of your hands and if you really must have a docked dog then you are going to have to try to find a breeder who will do this for you.