Here are a few links, the first shows you where you can find kefir grains. Most people will mail you some for free aslong as you pay the postage. I'm unable to mail any milk grains out as I dont have enough due to my own personal consumption. The other links explain how to produce the culture from the grains and the others provide information on the multitude of health benefits you will obtain.
In my personal experience Ive found that consuming the grains themselves have a much more powerful effect.
On the last link I suggest you read it to understand all the health benfits of consuming beneficial bacteria, if your really observent you will notice that one of the yeasts within keifr is called "candida kefir", dont worry its not candida albicans.