Have you ever been to Polka Deli in Orange? I've never been there myself. I keep forgetting to go down there. It's listed as a bakery:
newpoland.com/polish_community_bakeries.htm
My favorite place is Old World Village in Huntington Beach. Even though it's German, the Old World German Restaurant has some Polish food and the Deli has a bakery and a lot of imported stuff.
Polka Deli has got traditonal Polish delicacies as well as Polish imports. Dunno if babka is included. It is at 1710 Tustin Ave in Orange, CA. tel. (714) 974-8276