APRI - AMERICA'S PET REGISTRY INC, advertises free registration for commercial breeders, and was founded by commercial breeders and resellers. To me, it just means "Puppy mill." If your planning on becoming a breeder, please, don't just breed on one quality alone, size is just one part of standard, there are so many more important things to consider, such as, are your pets healthy? Many inherited disorders don't show up until the age of 3 when the dogs have already been bred. It's a good idea to have your pets thoroughly evaluated by a vet with proper health screening done. Here some information on the different registries.
Registries. I think AKC is the only registry that is worthwhile, most of the others will register anything, and need no proof, but take the breeders "word" on whether the dog was purebred.