In your area, there will no doubt be dog breeders for almost all the popular breeds you can think of. When you want to buy a dog, you can't just go to the local shops for one, and for good reasons. Pet shops selling puppies, should be avoided, both the puppies, and their mothers, could have been treated badly.
Registered Dog Breeders are almost certainly the safest and best way to buy a puppy. Breeders look after their animals, generally keeping them in good surroundings and having them checked at the vets and seeing they are inoculated.
Whatever type of dog you've chosen, you will usually find a breeder, somewhere! Even for the more rare types. Dog breeders might advertise on the web, in your local paper, dog and breed specific magazines. Once you feel you've found a suitable breeder, check them out with one of the good dog associations, like Crufts, and always visit the premises.
Once you're happy with everything, and decide you would like a dog from them, order your puppy. Good breeders, with good reputations, especially rare breeds, have waiting lists. Dogs only have two breeding cycles a year, so you might have to wait. But waiting for your pup makes picking them all the more exciting.