Acquiring quality Kefir grains is left to chance. The commercial sellers of Kefir grains do not certify or test their product. Most people get their grains from a friend or probably from a seller on Kijiji.
This is one seller’s description of his grains, which is probably more than acceptable. Milk kefir grains.
“I obtained my milk kefir-grains in late summer of 1978 from a local friend who has her own milking goats. The circumstances surrounding the fashion if which I was able to procure those milk kefir-grains, which I was on the lookout for about 3 years prior, is an interesting story in its own merit. The culture has been diligently cared for by yours truly over this time. Among the original stock is currently a mixture of now 12 other batches of milk kefir-grains which have been obtained from different sources around the world over the years. These are now mixed together as a single batch, to ensure best quality culture from all batches mixed together as one. This is my personal observation with much research on my part.”
They are now available at a premium here.