Which brand of cow milk did you guys start your babies on? And does it have to be whole milk or fat free?
Buy what you can afford. Conventional whole milk is least expensive, then organic, and the most expensive is grass milk. Some farmer's markets have raw milk, but it can be dangerous and in my state they have to label it "only for pet consumption".... I know families that use it though.
WIC gives me whole milk but I prefer 2%