never buy from a petstore.

i'm sure every breed has a local website with reputable breeder contact info, but adoption would be the way to go. they usually list any dogs up for adoption (purebreds) in the area if that's what you're set on.

i personally like the welsh corgi, but when the time comes to get a dog, i'll probably go to the pound.

 

+1

There are also breed-specific rescue organizations if you're looking for a particular breed. The AKC has a great list of breed rescue organizations here, and of course a list of breeder referrals as well.