When somebody wants to buy a pet from a breeder, it is just that, a companion animal. Breeders who care about the breed, health, and quality will not sell a dog to someone in tact who does not have the education and training in the breed to become a reputable and ethical breeder. These dogs are less in price because you are not purchasing breeding rights to their bloodlines. If you do not get the animal spayed or neutered by the time it is a certain age it leaves them with the impression that they have been lied to and stolen from.
That being said, when they sell a show/ breeding prospect to someone, they are selling breeding rights to their bloodline, and a promise to help educate and train that person in how to go about becoming a reputable breeder who will in turn breed for health and quality.
Breeding dogs the right way is full of hard work and worry. It is not for everyone.