Because Costco carries so few SKUs, each buyer manages a very small number of supplier relationships in extraordinary depth — tracking commodity prices for ingredients, calling back when cocoa prices fall to negotiate lower prices for members. Unlike Walmart's adversarial squeeze model, Costco's approach is 'tough but fair': suppliers trust that Costco won't mark up their product 50% after negotiating hard on price. When Costco cuts costs, 89 cents of every dollar saved goes to members.