This is a good place to start looking for Birman breeders in the area.http://www.birmanbreeder.com/
As far as finding a reputable breeder, send one an email asking about kittens. Since you already have a Ragdoll, I assume you would be able to tell what kinds of responses would indicate a responsible breeder, and which ones you might want to be wary of. You can always ask us if you get some responses you're not sure of! Hope that helps, you'll love a Birbaby if you get one - I know I love my two little boogers to death!