I think either way you should get one from the shelter. There are more purebred animals in the shelter than people seem to assume. Not to bash any particular breed, because I know German Shepherds are lovely dogs, but a lot of times they have some very serious problems with their hips. They are a very smart breed, but I would suggest going for a mutt. A lot of time animals that have been bred to meet a breed standard suffer from being bred within too narrow a group, or from the bad genes being carried on both sides, causing the puppies to inherit these traits. They end up having a lot of problems. Mutts often escape those problems.
I think that everyone should get their pets from the shelter system. Animals are being put down in shelters every day. Buying from a breeder allows them to keep breeding, which means more animals will be put to sleep. Shelters have puppies, pure bred animals, and animals that haven't done anything wrong to make them lose their home. Often animals lose their home because people move, or develop an allergy.