Goodluck with finding your little ones! I was lucky to find a tiny girl from a very good breeder in kent, she has been a hobby show/breeder for 46 years and shows at Crufts every year, one of her bitches had 2 pups, the male she is keeping( he was alot larger than Pixie!) Pixie just came out too small to show & breed so she was selling her to pet home only..sometimes you just get lucky! I think it is best to avoid those breeders that just breed specifically for tinies and find a reputable breeder that just happens to have a puppy that just came out smaller than the rest!
My breeder did NOT charge me more money for this little girl..although some money grabbing breeders would have! (and would probably have got it!) all she wanted was a lifelong loving home for this special little girl.