
I would always advise contacting the breed clubs, most of which will have a breeder/puppy list. You may hav to go on someones waiting list, but this is better than buying a commercially bred pup (sadly it is a breed very popular woith puppy farmers who don't care about health testing, or temperament). The parents should be heart tested, and preferably from parents that were heart tested, as the breed does have a high incidence of heart problems, which the good breeders are working at eradicating by ensuring the breed fromstock whose parents have shown longevity.
If you get to see several generations up to old age at the breeders home then you will be fairly sure that they come from a long lived line (as the heart problem in the breed often causes death before 5 years of age).
In toy breeds that have smaller litters bitches are often hard to find, as naturally the breeder may want one for themselves to carry on their line.