To find a reputable pitbull breeder, use a breeder classified search, such as the one available on AKC.org as of 2015. Look for a breeder that screens breeding stock for any health problems, has an appropriate environment for breeding and raising dogs, and provides documents. Both the breeder and prospective buyers should ask each other questions during the adoption process.
To use the breeder classified search on AKC.org, choose the Find A Puppy page, select a breed from the menu, enter a ZIP code, set a search radius and perform a search. The site classifies pitbulls as American Staffordshire Terriers. One benefit of finding a puppy through the American Kennel Club is that breeders who register dogs with the club must have purebred dogs with the appropriate documentation, and the club inspects breeders to verify that there aren't any problems.
Ethical dog breeders breed dogs to better the breed, so they don't breed dogs with health problems. Ask the breeder for documentation verifying that the breeding stock and puppies have a clean bill of health.
A breeder's facilities should be clean, and the dogs should receive regular exercise and attention. Watch how the breeder interacts with the dogs, and make sure the dogs don't shy away from the breeder or from strangers.