All of the retail shops and restaurants at JIA have concession agreements with the JAA.  Within those agreements is a pricing regime called “Street Pricing Plus 10”.  Simply put, these vendors can charge no more than 10% above what a similar store off the airport would charge.  The key to this concept is similar store.  You might be able to find a product substantially cheaper at say a Walmart but it is more likely that a 7/11 type of store is used for comparison.  Where a brand name has a location at JIA, prices should be no more that 10% above the prices at the same brand off the airport.  JAA staff periodically monitors prices and compares them to appropriate locations off the airport.