You can also buy great kefir grains from Premier Research Labs (Nutrient Research). Their # is 310.320.1132. I don't think you can order online. They have excellent high quality products & I think the grains actually originate from Teldon in Canada. I know GEM is also good as others suggested.
Re: yogurt maker. The naturopath I work for suggests not using any EMF when culturing live foods because it can cause mutations in the process. So I never culture w/electric appliances but actually leave my milk out for 4 days on a high shelf in your cupboard usually adding the juice of 1 lemon as the Indians do (& they make excellent yogurt). Start w/Claravale raw milk vs. pasteurized if you live in CA--otherwise I know it's not so easy to get good hi-quality jersey milk. Aajonus Vonderplanitz, big raw foodist, heavy proponent of raw milk advocates making yogurt this way and he doesn't heat the milk first. I do heat milk when I'm making kefir. I've made cottage cheese & yogurt w/o heating many times & it's excellent. If you need to create a warm incubatory environment, change out your lightbulb in your stove to about 75 watts and for 12 oz, kefir usually cultures in anywhere from 7-12 hours depending on temp in your home.