Well, I am by no means an expert.....haven't actually quite gotten to kefir yet, as I am re-hydrating grains and they are still a bit in shock from the insult....but you put the grains in milk, and let it sit, then strain out the grains and start again with more milk. Just like yogurt, but easier. Room temp, it sits on the counter, and you take the grains out to culture your next batch with. They apparently grow over time, so you end up with more grains to share.
I'd pay the $8 for fresh, live grains. But check around for a kefir-share site, there are often people who got their grains for free who will "pay it forward" to you. I got my kombucha that way. I have since passed it on to many people.
I would offer you some grains but mine are still tiny and I have a short list of people that the first few batches are promised to. If you don't find any, check in with me in.....um.....I have no clue!