That's basically Costco, the price they pay is what you pay, the system paired down to bare necessities, and it is incredibly popular.
Costco mandates a maximum of 11% margin on goods in the store and aggressively monitor suppliers on that cost.
One of the reasons I like costco actually 10% or so is a fine margin to pay.
The transparency just isn't there. I would love to see a reasonably complete breakdown of the final cost of every item