A one-ounce gold bar and a ten-ounce silver bar are on display at a Costco warehouse in Wisconsin. A one-ounce gold bar and a ten-ounce silver bar are on display at a Costco warehouse in Wisconsin. Dominick Reuter/Business InsiderA one-ounce gold bar and a ten-ounce silver bar are on display at a Costco warehouse in Wisconsin. A merchandise pickup slip is used to buy precious metals at a Costco warehouse. Metals dealers and advisors generally recommend planning to hold onto physical precious metals for the long term.