BECAUSE BYPASS IS COSTLY.  Cold Spring Shops may have to offer a Fourth Rule for Travelers^(*).  Never buy snacks at a gas station.

Gas stations that don't sell consumer goods will tend to have higher priced gas, [AAA's Beth Mosher] added. That's because stations with consumer goods items derive a majority of their profits from selling items such as chips and pop as opposed to gasoline itself, she said.

The trick, though, is to stockpile the road-trip supplies more cheaply at the grocery store before you go.

^(*)The other three rules are Never buy shaving supplies at the hotel, Never buy film (now, digital-camera batteries) at the amusement park, and Never buy beer at the airport.