Since no gun stores exist in Walnut Creek or Lafayette anymore:
City Arms - Pleasant Hill on Golf Club Rd.
USI Range House - Concord
Big-5 - Walnut Creek / Concord
are your best bets.
Why not buy in Sac where you live? Lot's of gun stores in the valley.
I'm always looking for a square ammo deal in my travels. You can never
have to much ammo!
Good luck. -g