Where to buy sauerkraut juice in the bay area
fresh sauerkraut juice from Farmhouse Culture - they are at many farmer's market throughout the week
I sometimes take my fresh kraut and run it through the juicer - you could do the same - buy some of farmhouse culture sauerkraut - they are stocked in most Whole Foods Stores in the frigerated section...and than juice it your self...
Their kraut juice is only available at the market - get there early - it sells out quickly!
How much do you need? I actually have tons of extra juice in my homemade kraut jars in the fridge but am unfortunately out of town and won't be back till after Christmas. But if you were willing to put up with a minor amount of inconvenience you could probably get a passable juice by then if you a) started making a batch of sauerkraut tomorrow and b) stored the jar somewhere warm to hasten fermentation. It's a lot easier than you think, requiring cabbage, salt, a jar, and preferably something to weight down the cabbage.
If that's out of the question I'd try a German specialty store like Lehr's on Church in SF first, maybe a Russian deli next.