Cosco only sells Choice grade and higher meats. During the holidays they may also carry many prime cuts which are not generally available at smaller stores. I would be that if the price was half the price per pound, the quality was of a lesser grade or the small retailer was running a sale. Costco does not use loss-leaders such as these to lure you into the building hoping to make up the loss by also selling you something else.
In general their pricing will be equal to or better than other retailers with a higher quality and trim spec than their competitors. If you are paying for bones and fat at a lower per pound price you are not getting a deal.
Costco doubles the manufactureres warranty on most electronics from 1 to 2 years and provides free electronics concierge service as well. Which other retailer does that at no additional cost? So if you are price shopping you can beat Costco prices, but you will not beat their warranty or customer service….just sayin’!