...And there is a limit to what you can do there...
I'm just remembering what I saw at the Ohio State Fair in 2003. At any concession joint I could buy a 20-oz bottle of Coke for $2. I didn't, though, because across the midway I could buy a 20-oz Coke from a vending machine for $1.
Apparently whoever set the price for the fair didn't have control over the machines...!
--Dave Althoff, Jr.