Research shows that people who shop with credit cards pay 12% to 18% more than those who shop with cash. Think about it, shopping with $40 in your wallet is a lot different than shopping with a $10,000 credit limit on a piece of plastic. Try shopping with only cash or your debit card if you want to save some money. Following this one tip alone can save the average household well over $2,000 a year if they are used to putting everything on credit.