Costco Wholesale (NASDAQ: COST) and Walmart (NYSE: WMT) are the two largest discount retailers in the industry. This has helped Costco and Walmart provide market-beating returns this past year. Costco is down 5% and Walmart is up by 6%.
Costco is a very popular warehouse club, and for good reason. Costco's house brand, Kirkland, also offers many products that have devoted fans reaching for their credit cards. In fact, finance expert Dave Ramsey warns about a common error you need to avoid so you don't end up wasting money even as you're trying to save some cash.
Image source: Getty Images We often compare prices when buying big-ticket items like electronics or domestic appliances, but it isn't as easy to do when it comes to grocery shopping. For starters, products come in different sized packages, so you need to calculate the per-item cost.