Augusta to Bangor to Machias via Airline?
My info may be outdated, but the Airline Snack Bar went away some years ago. Has it been resurrected? Used to be a pretty good breakfast/quick bite place.
The Airline runs from Bangor to Calais inland; to get to Machias, you'll have to take a road that cuts from the Airline over towards the coast.
Your best bet is to eat in Bangor or Machias and have snacks on hand. The Eagle's Nest on Rte 9 in Brewer has a good local reputation. Pies and baked goods are good, although it's the wrong season for strawberry pie with whipped cream!