An easier and more pleasant journey with your chosen Boxer starts with checking out parent dogs for unbecoming traits like aggression, hyperactive and extreme shyness. This is easier to do when you get your Boxer from a reputable breeder or from a pet shop that get their animals only from known breeders.
Exercise prudence if you are getting your Boxer puppy from pet stores, which often get their supply from breeders of unknown reputation.
These "puppy mills" as they are called are not known to put much emphasis on quality and health of pups they are producing.
Reputable breeders would adhere to accepted standards for Boxers in terms of uniformity in breed, good health, temperament, size and color.
Reputable breeders would be able to show pedigree and registration papers and/or pictures of parent dogs that may reside somewhere else.
Professional breeders are also there to produce dog show champions or prospects.
Even if you are not looking to raise a show champion Boxer, known breeders can provide you with some "best buy" puppies because not all puppies in a litter are show prospect/champion materials.
But full litter would have had benefited from same proven bloodlines, nutrition and medical care. So you can choose from among good-looking brothers or sisters of potential champion for a bargain.