A new book about Costco written by two superfans is unveiling secrets about the discount retailer, with the unusual blessing of Costco itself.

Costco is famously secretive about aspects of its business, including who actually manufactures its Kirkland Signature products. When authors David and Susan Schwartz initially began researching “The Joy of Costco: A Treasure Hunt from A to Z,” which came out on Sept. 12, Costco refused to participate, they said. But according to an interview with Eat This, Not That, Costco executives did reach back out in 2021 and agree to confirm some details, preferring the book be accurate if it had to exist at all, Susan Schwartz said.

One of the most interesting tidbits for Costco shoppers is an easy visual clue that something is even more discounted than a typical bargain item. “If you see a price that ends in something other than ‘.99’ it means either the vendor or Costco is offering additional savings,” the Schwartzes told Apartment Therapy. “Items on end-aisles are often reduced in price.” 

If you’re looking to stock up before something disappears — a sad but common fate for many items at Costco — check for an asterisk on the upper right corner of the price tag. That signals something is about to be discontinued, the book says.