Yogurt is 2.09 a quart. Milk is around 3.50 per gallon. Using this logic, I deicided to try to make yogurt at home to save money. You'll need a thermometer that goes from 100 F to 220 F, gallon/half gallon of milk, 1 or 2 cups of yogurt, a large glass jar (or old yogurt containers), a towel and a warm place to keep the yogurt for 7-14 hours.
Pour the milk into a large deep saucepan and slowly bring to a boil (if you have a large capacity double boiler, use it!). Put the yogurt in a bowl at room temperature and allow to warm while the milk heats up. bring the milk just to a boil and remove from heat. When the temperature reaches around 105 F, whisk the milk and yogurt together and put into the glass bottle. Close the bottle gently (less than finger tight) and wrap in a warm towel. Place in a warm spot (or in an insulated cooler) for 7-12 hours, then refrigerate.