Examine shelf labels to compare the cost per unit. While the prices of bigger containers often run 15% to 30% less per unit, there are exceptions, so don’t automatically reach for the largest bottle or jar. In summer, look for big sales at your supermarket on ketchup, mustard, and mayonnaise, which will be discounted by as much as 30% for barbecue season, says Julia Scott, the founder of BargainBabe.com, a money-saving website.
Annual savings: $206
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