Mayflower Market in Chinatown Mall often/usually has them, as well as a good percentage of the various other Chinese markets throughout Chinatown.
I almost always see them at both Issacson & Stein and at Rubinos. Treasure Island locations often have them as well.
For a traditional oyster stew, you most definately need the oyster liquor. Add the oysters at the very end of cooking to gently poach them, or you'll end up with a nice broth and oyster flavored raisins.
"Bass Trombone is the Lead Trumpet of the Deep."
Rick Hammett