Making yogurt is really easy and is about 1/2 the price of what you buy in the store. Oh and it tastes really yummy also. All you need is milk, a glass jar and a starter. I filled my 1 quart mason jar and then put a little less then 1/4 cup of yogurt from the store. Once you make your first batch you can use that as a started to make more.
Mix it in with the milk and set it in a warm place for 8-10 hours or less depending on how quickly yours goes. Make sure that the place is around 90-100 degrees. I put mine by my wood stove. Others use a dehydrator or a heating pad. If your have a crock pot that has a warm setting (test it to make sure it's not too hot) fill it up with water and place the jar with a lid on it in the water. If your area is too hot then the bacteria from the yogurt that you placed in will die and all you will have is curdled milk.