Getting numbers for these kinds of things is quite difficult, since a lot of it is negotiated with a salesperson and is based on a mix of the quantity you’re looking to buy and the value you present as a long term contract to work with (i.e. how much other stuff do you buy, and how regularly).

But let’s look at examples to demonstrate the point. This article claims Costco sells 25lb flour for $13 and that matches my local experience (mine is actually milled and bagged like 5 miles from my house, which rocks). That works out to 3.3¢/oz. If I order the same brand (King Arthur from the article) for pickup from Walmart, a 5lb bag will cost $5.24, or 6.6¢/oz, or roughly double. Walmart’s store brand is actually a little cheaper at $4.34 for 10lb bag, or 2.7¢/oz, but that’s going to be a bit different in terms of quality. If you go to your local grocery instead (not Walmart), prices will be another 10-30% higher in my experience (like $7-8 for the same 5lb bag of King Arthur flour at my local grocery). If you’re a bakery, you’ll be able to get even better prices on flour.

Your local coffee shop isn’t going to be buying their beans from Walmart or Costco (though they may get their milk/creamers from there), but I’d expect the cost difference to look similar for low volume vs high volume shops. So something like 10-50% cost difference, depending on the item.

But that’s a pretty small percentage of the overall profit margin equation, especially for coffee where costs are more dominated by labor than ingredients. And in this case, larger orgs win again, here are some examples:

• benefits plans are cheaper in bulk - mostly due to administrative and marketing costs
• admin costs of larger businesses can be spread across more stores - payroll, marketing, etc can be shared
• larger chains get more customers due to more brand recognition (higher marketing budgets, better locations, etc), thus more served per employee

And so on. Larger orgs have lower base costs, their marketing dollars go further, and they get higher volume of customers. So the only way for a smaller business to compete is to offer something different, so they usually focus on overall experience (quality of service, interesting branding, etc) instead of cost. If they tried to compete on cost, they’d lose.

Their fillings are freely available on their website and will give you some insights, but they don’t get anywhere close to their unit price for coffee.

That said, their most recent 10-Q says things like

Depending on market conditions, we may enter into coffee forward contracts, futures contracts and collars to hedge anticipated cash flows under our price-to- be-fixed green coffee contracts, which are described further in Note 5.

They do the same for other commodities. It would probably be difficult for a small scale player to participate effectively, if at all, in reading commodities to try to minimize commodity cost.

https://investor.starbucks.com/financial-data/sec-filings/default.aspx