That I REALLY have to disagree with. While some might do it for the money (puppy mills) not all breeders do. By the time you consider the fact that the breeder feeds the mother, possibly the father, and pups, shots for all, veterinarian bills, and many, many other expenses.
A true breeder does it for the love of the animals and in the end after expenses makes VERY LITTLE. Also true breeders (at least those with ANY amount of class) care for the puppies as though they are their own.
Every litter we have leaves our house leash trained, with basic sit and stay commands, puppy shots up to date, a requirement that the new owner will have the puppy checked out by a vet within 72 hours, full rights that if I find out the dog is being mistreated to reclaim the animal, and now thanks to NickP's suggestion crate trained.
My two that I kept out of our last litter I do not even close the crate door at night. They know when it is bed time to go lay down in it and go to sleep.