Not all purebred breeders are the same and, judging from the response you have gotten from yours, I would say they are not among the best.
If you decide to get another dog, I strongly suggest you go through a reputable rescue group. Cost should be within your budget and any dog that you adopt will be temperament tested and they will know whether or not it is good with children.
FYI - a bait dog is one that is used to train fighting dogs. If you do rehome this dog yourself, you need to disclose the fact that he is aggressive towards children and you need to make sure that you check references.