Cheapest place to buy alcohol in the nor cal area?

[TBag]

I figured 2+2 would be the best group to answer this question. Anyways, I came up from So Cal and I actually have very little experience buying the booze myself, so what do you guys recommend? Choices include, but are not limited to, stores such as:

Safeway (Vons)
Costco
Sam's Club

You get the idea. Anyways, help here would be greatly appreciated!