One way to try it would be looking up specific plants desired in THE PLANT LOCATOR - WESTERN REGION sourcebook and seeing who comes up. If you are looking to buy wholesale, and qualify to do so, try the online OAN Buyer's Guide.

I get just about all my native plants from Hansen Native Plant Nursery near Salem, OR, and Burnt Ridge Nursery south of Chehalis, WA. I like them both.

http://www.burntridgenursery.com/

Here is a link that might be useful: Hansen Nursery