Have you recently purchased groceries in Idaho, Utah, or other Midwest states? Did you mumble that groceries are much cheaper there than here in Washington?. Idaho is, on average, the third cheapest state in America to buy groceries, trailing only Kansas and New Hampshire. According to Zippia.com, residents in New Hampshire spend an average of $183.00 per month on groceries, compared to Hawaii (the most expensive), whose residents pay $556.76 monthly.