We here in the Bay Area are blessed with several reputable stores from which to buy our snakes. Everyone seems to know about the East Bay Vivarium, and while the Vivarium is hard to be beat for the sheer variety of exotics, there is another store which is also as fun to visit and has a great selection of healthy, well-cared for herps.
Petacular Exotics is in Antioch and frequently sells animals on Kingsnake.com. I have bought three snakes from them in the last 5 months and not only are the prices fair, but the animals are impeccably well-cared for. The owner also specializes in geckos and the staff is helpful, knowledgeable and friendly.
I highly recommend checking them out.