This is the easiest thing to make in just a few steps, one pan and one thermometer. Cost? About one dollar for two-three cups of Greek-style yogurt. If you purchased the same in the store, expect to pay over $3.00.
Here is what you need:
One quart of milk
2T of yogurt mixed with 2T of milk
Bring the milk to a boil and remove it from the heat source to cool to 100 degree.
When the milk has achieved the right temperature, mix in the yogurt you have mixed with milk. Cover the pot with towels and let it sit in a cooler overnight or 12 hours.
Refrigerate and use in your favorite recipe.
Mine? Fresh berries and a teaspoon of honey.
I make a batch every week.