A spayed or neutered dog is of no use to a puppy mill and will therefor eliminate a reason for a puppy miller to steal your dog. Also if your dog is bred, even accidentally, each of their puppies, or their puppy's puppies have a risk of ending up in a puppy mill breeding program no matter how carefully you think you screened your puppy's buyers. An even better alternative to buying a puppy is adopting a dog from the local humane society or shelter. Breed rescue organizations are also spread throughout the US to save purebred dogs. Often shelters and rescue organizations can provide you with a loving pet and you are saving a life too.
Crossbreeds can be just as good a pet as any pure bred dog.
Shelters get dogs of all ages, sizes and personalities and it should be possible to find one to match your lifestyle. There are many advantages to getting a mature dog over a puppy. You can see what your dog will look like without unexpected size, weight, or coat type. Many are mature and well mannered in houses and have outgrown the chewing stage. It is much easier to see what a mature dogs personality is like than a puppy that is ever changing with hormones and growth.