No, those are Costco’s suppliers which are completely invisible to the customer and completely different. Costco purchases the items from the suppliers, genera

No, those are Costco’s suppliers which are completely invisible to the customer and completely different. Costco purchases the items from the suppliers, generally. They then resell them to you for a markup. With few exceptions, every single item in Costco is sold by the first party seller: Costco. So my point stands: third party sellers are generally not a part of the Costco experience.