[header] How to buy kefir grains [title] Determine whether you want to buy fresh kefir grains or powdered kefir cultures. [step] Fresh kefir grains are the preferred choice for people who prepare kefir regularly. These grains can be continually propagated with minimal effort, so you only ever need to buy them once. 
Powdered cultures, consisting of dormant yeast and bacteria, are a more convenient option that can be stored easily and do not have to be monitored. However, the powdered form does expire and needs to be repurchased periodically.