ISO Buttermilk powder
I know Rainbow has buttermilk powder in bulk, but I'd like to find it pre-packaged (and closer to Nob Hill if possible). Whole Foods and TJs don't carry it in any form. Does yogurt make an acceptable substitute for buttermilk in baking and pancakes?
The second part of your question should be asked on the Home Cooking board.
I've seen powdered buttermilk in cans. Also, buttermilk freezes pretty well if you want to buy a quart and freeze it in smaller amounts.
I think you can find it at a regular grocery store like Safeway in the baking aisle. I have a tub by Saco.
why go for pre-packaged? seems silly to NOT be able to get an amount determined by you? if you hop on the 27 bus, getting to rainbow is pretty darn easy.
I know this isn't your question. But texture and flavor are better when you use buttermilk not made from powder.
And re the second part of your question: yogurt and buttermilk are generally pretty interchangeable.