I would like to take this time to post a list of Dog Rescue Groups. The AKC has recognized the need to recognize that there are loads of opportunities to obtain a specific breed. Our shelters are loaded with purebred dogs because many times people purchase them without researching the breed. Cocker Spaniels, for instance, while a family dog can be nippy towards strangers. Labradors are loyal and loving breeds, but can become very upset without constant attention. Many times people purchase dogs because they are so cute as puppies, but they didn't take into account they grow and the owners are not prepared to handle that.
As with all shelter dogs, purebreds can be trained out of negative behavior. Older dogs are usually the most difficult to find homes for, so if you are considering a specific breed, think about one that has passed the difficult puppy stage.
My rule of thumb is to see how many dogs are available for adoption at a rescue. Ask detailed questions about the dog's personality and don't gloss over the facts about your commitment because you fall in love with the looks of the dog.
Good luck with your search,