I don't know anything, really specifically about Poms, but I do know that with any of the toy breeds especially, you really have to be careful to avoid backyard breeders and the products of puppy mills. I think that may be because these people can cram more dogs into a small space, increasing their profit potential.
Do your research, not only on the breed, but check potential breeders very, very carefully. Ask to visit. If a breeder is "real" they will be happy and proud to show you their dogs. They will also want to check you out before they send one of their puppies home with you.
As an example, we are in regular contact with the breeders we got Kharma from (and have become friends), and we also stay in contact with the people Shiva came from. She was a different story; a man and his son, who have about 200 acres with a variety of animal (rhea birds, burros, goats and a couple of horses) had an opportunity to breed their Fila to a friend's dog brought from Brazil. They basically breed for their own dogs, and don't have any regular litters, but they understand what they are doing and the principles of sound genetics. These are the kinds of things to look for when you want a puppy.
Sound people make sound dogs.