Yeah, it's easier to buy kefir.
First you have to get the culture which is a mix of bacteria *and* moulds and apparently it takes a long time (ie not just overnight) so you would run a risk there too (unless you had perfect incubation)

And trust me. I ran a tiny dairy for several years and made everythign - quark, yoghurt, sour cream, camembert, gouda, fetta, haloumi, butter.
I still make *all* our family yoghurt and 50% of our family cheese. If I could make it at home I would. I buy from a Russian immigrants' shop

Good for you Pyxi - pm me if you need advice