Contrast to markups of 25 to 50% for typical retail, and for generic drugs in the thousands. https://www.thepharmaletter.com/article/1-000-pharmacy-mark-...
However, their financial statements do indicate an 11% average gross markup.
But there are definitely plenty of products marked up more than 18% at Costco. Either that or they are paying way too much for some things.
Contrast to markups of 25 to 50% for typical retail, and for generic drugs in the thousands. https://www.thepharmaletter.com/article/1-000-pharmacy-mark-...