There is a kefir web page and the lady who runs it is Gizelle. Here is her webpage http://www.your kefirsource.com or email her at Gizelle@yourkefirsource.com. She buys grains and resells them.

I use churned buttermilk for baking when I have it (I have cows). I also make cultured for my cheesemaking and put it into ice cube trays for later use. I have used kefir for baking also and it is very good. I don't really have a preference except what I have so I don't go to the store. I only buy an occasional fruit or vegie or pet food.