Hmm...I don't speak German very well but this site has a few dogs. Not sure how many may still be available for rescue. I wasn't very successful in finding many rescue sources but they may know of any local shelters or other rescues if they don't have anything available currently, or can put you on a watch list if they get anything in that would fit what you are looking for in a dog.
In general when finding a breeder the best way to find a reputable breeder is to go to events and talk to people who are competing. Go to dog shows or agility trials or pulling leagues and talk to the owners of the dogs being worked. Find out if they breed or where they got their dog from. Dogs being worked successfully are dogs that tend to be proven healthy and that is ultimately what you want. Many backyard breeder/pet quality dogs might be pure bred on paper but if you actually wanted to work them or do long trail running with them they won't hold up because they aren't bred to standard and the parents aren't health tested before breeding. It's a little hard with out of country since we don't know what is standard expectation from a breeder in various other parts of the world, but I would think no matter the part of the world puppies from breeders who work/show their dogs are going to be a safer purchase if you are looking to purchase a puppy from a breeder.