Costco’s gold bars and silver coins continue to be bestsellers – and they’re also a code to boost your online sales

Analysts estimate the company sells about $200 million worth of gold and silver a month, and former CFO Richard Galanti said the inventory typically sells out “within hours.”

A large part of their appeal to both professional and amateur collectors is the fact that bars and coins are sold at a very low margin over the spot price of the metal. (U.S. Mint silver coins are more expensive because they come with tax benefits.)

Channeling hundreds of millions of dollars in sales through Costco.com is a quick way for the company to demonstrate strong e-commerce growth with relatively little risk or complex capital investment: it simply buys a lot of gold and sells every ounce of it to members.

The strategy is also paying off, with digital sales this quarter up 20.7% compared to the same period last year, before Costco gold went viral.

And since gold and silver are members-only, buzz around the metals is another way to attract new sign-ups. After all, what is a $60 membership fee for a shopping cart of $4,000 worth of gold?