Some items might even be at a loss for Costco ($1.99 for pack of 36 water bottles?) but overall I think it's not zero margin enterprise. Some items or services

Some items might even be at a loss for Costco ($1.99 for pack of 36 water bottles?) but overall I think it's not zero margin enterprise. Some items or services are definitely carrying healthy profit and behind the scenes kickbacks from the vendor (small business payment systems, other recurring services sold to customers, very large price ticket items like furniture and cars)