Going OT here, and a bit of a rant.
TL:DR - not all purebreds are overpriced and horrible - see why!
All the discussion about pure-breeds versus mixed breeds? It all depends on the genetics! Mutt from the shelter - cute puppy - how big is it going to get? What is its temperament? What is its previous health history? Intentional cross (i.e. golden doodle) - what are the genetics of the parents? If both parents are from breeds with the same known genetic issues (i.e. golden retriever, standard poodle) then the cross may also have those issues, depends on the parents.
Backyard breeder =/= hobby breeder. Backyard breeder - in it to make money, no genetic testing of parents, often horrible socialization of puppies. Or thought that because their bitch is so cute, they can breed her and make money.
Hobby breeder - pays attention to genetics, will have shown the parent, puppies are in the home, well socialized.
Responsible breeder/kennel - has more than one dog but only one breed (may be two breeds if husband and wife each have own breed), shows, knows genetics, does the genetics testing, those $1000 - $1500 puppies are being sold at a net loss. They are in it because they love the breed, ad are happy/relieved if they break even
Puppy mill - lots of different breeds, no genetics testing, horrible living conditions, puppies will be expensive but low quality, health issues, no socialization. Puppies usually sold on-line or at pet stores. No guarantee that the pedigree that comes with the pet store dog is that dog's pedigree, since dogs and paperwork tend to be shipped separately.
How do you tell a good breeder? First, they will grill you about the suitability of your home for their precious puppy. Their dogs will be good representatives of the breed - (depending on the breed this may mean CKC/AKC titles, working titles, whatever is appropriate). They have done the appropriate genetics/health testing for their breed. The puppies are properly vaccinated. They know the good and bad developmental periods for a puppy to move to a new home. The puppies are used to being in a house and are socialized. There are no hassles about registration, they will have registered the litter with the appropriate group (CKC, AKC, whoever) and will do the transfer to the new owner. If they ask extra $ for this, they are not reputable. Also, many breeders have strict policies about restricted breeding (i.e. you agree to not breed unless certain conditions are met, if they are not met you will spay/neuter the dog, if they are met they will mentor you and you have just become a hobby breeder). They will take the dog back if there are problems instead of it going to a shelter.
The more popular the breed is, the more careful you have to be about your source. Purebreds at shelters may be wonderful, but they may also be puppy mill dogs with all the attendant issues. Breed rescues will do the care to bring these dogs to the best health and behaviors status they can, but some things can't be fixed.
Why all this? Because humans have spent several thousand years breeding dogs for various uses, and problems have crept in because of the limited gene pool. But then we know what we are getting. Border collies want to herd. Shelties want to herd. They will give you the eye - you can see they are trying to figure out how to herd you. Terriers are scrappy -what sensible dog will go down a badger hole or take on a rat that is bigger than it is? Working dogs want to work. 101 Dalmatians did Dalmatians such a disservice - they are carriage dogs, meant to run under a carriage for 10 hours a day - and then they are house pets and sit around and get fat because this is the wrong environment for them.
Cats on the other hand - a nice domestic sort-hair from the shelter (or some one's kittens) will be fine, usually. Just make sure you have the vet checkup before you lose your heart.
Background - my adult life has been enriched by three cats from rescue, and three pure-bred dogs from responsible breeders. No major health issues. My parents' first 2 dogs were, we think, puppy mill dogs - one had obviously had parvo virus before we got her (adult teeth gave it away) but was otherwise wonderful, the other had epileptic fits which got worse and worse, we had her euthanised at 2, and it broke our hearts to do it.