bitt24/shutterstock Chicken of the Sea Chunk Light Canned Tuna Costco:$14 for 12 7 oz. cans (16.7 cents/oz.) Kroger:$2.59 for a 12 oz. can (21.6 cents/oz.) Savings at Costco:22.7% (4.9 cents/oz.) Brent Hofacker/shutterstock Greek Yogurt (Store Brand) Costco:$5.59 for a 48 oz. ...