So, I went online and looked at all those fancy yogurt makers cuz I thought I needed one to make yogurt. Wrong. Some kind soul set us all straight in the product review (!) and said all you need is some kind of place that will heat the milk to a temperature of 120 degrees consistently over 6-8 hours. Investigating further, I found out that people made yogurt in the old days on the back of a wood stove (which gets hot!) and in the new days on assorted electronic devices like heavily used DVD players, for example, (which don't get that hot). So, I thought, this can't be that hard. It's not. And so far the only common denominator I have found is some kind of heat source (however erratic), milk and starter culture. I even left the last batch in the cold oven all night (forgot, oops) and it was so fine. Better than fine. It was YUM. The longer it sits, the tarter it gets. Oy. Did I mention you can save a lot of money doing this? I used to pay over 4$ for a quart of yogurt. Now I pay just under 1$ if you don't count the time I spend mixing it up and forgetting about it.
So, get a gallon (or half-gallon) of locally produced milk. It should be pasteurized, so you don't have bacterial interference, but it can be very lightly pasteurized, and you could do it yourself at home by heating raw milk on the stove top if you are so lucky to get some of that good stuff. Take a very clean pint jar and fill it almost to the top with milk. Stir in two tablespoons of yogurt from the last batch or (horrors!) if you have to, store-bought yogurt with active cultures. I use Stoneyfield Farm Organic Whole Milk Plain cuz I like to eat it and they do good things in the world, generally. Place the pint jar (and 3-7 other jars if you are ambitious) in a baking dish, heat the oven to about 200 degrees and pop those babies in. Leave it for an hour or so at that heat, er, until you remember, or after you get that load of laundry done, and then shut if off. I have a gas stove, so I'm paranoid about leaving it on at low heat for hours. But it doesn't need to heat continuously and you can save the energy and the atmosphere by just firing up the oven every couple of hours for about 6 hours to maintain some heat. But like I said, I forgot my last batch overnight and it turned out fine. Resist the urge to poke around and stir it cuz, it seems to resent being disturbed (I don't know why). Anyway, look in on the little white jars of happiness every once in a while and bless their multiplying cultures and in no time you'll be enjoying some yumminess with your local blue berries. Good luck!