When buying yogurt, don't buy the individual 6 oz. containers. Go for the larger 32 oz. container, and divide it up. The smaller portions can cost about $0.60 each. If you divide it up yourself, you will only be spending about $0.38 per 6 oz. The larger size still comes in a few flavor choices, not just vanilla.
When I make my daughter's lunch for school, I buy the bigger size and divide it up into 4 oz. portions.
