Rant: I was paying for airport food for years before a stranger in Bangkok set me straight

I always bought a sandwich and drink at the airport before a flight, thinking I had no choice. Last trip, a guy next to me at the gate in Bangkok pulled a full meal from his bag and said, 'The 7-Eleven across the street is a third of the price.' I felt so dumb. I'd spent maybe $15 extra every trip for a decade. What's your go-to cheap airport food spot you wish you knew about sooner?