1)  Breed rescue organizations. 

2)  Shelters do sometimes have purebreds - you have to be patient, but if you let them know what you're looking for, they may happen to have what you need.  Our Raggie, Harley, is a shelter baby.  The shelter recognized him as a purebred but thought he was Siamese.  Boy, did we get surprised!!

3)  A "retired breeder" - Breeders retire their show/breeding cats at some point.  Either the cat did not show well or had problems breeding, or is ending a "career." Or sometimes a breeder wants to quit breeding. They're usually (not always) adults, usually between 2-6 years old, and often available for much less than buying a purebred kitten.  My first two Scottish Folds were retired breeders, 14 months and two years old when I got them.  Wonderful cats!

Cats_Dolls