Sounds like she (the breeder) has no clue what she was doing when she bred and still has no clue! Did you ask her if this pup has been checked by a vet? Has he had shots? If you can afford it, take him to YOUR vet and have him do a health check. A head wobble could indicate a neurological issue or it could just be nothing, but a vet check on your part would be the best thing before you decide to lay down $500 for a dog!
A person may be a nice person, but a bad breeder! You'd hate to get a puppy that is going to have nothing but health problems! I know he is cute, they are allll cute (as Im sure you know)