| Nonstop Flights: Austin to/from Liberia, Costa Rica $218 r/t [February-April] â American Airlines American Airlines has round-trip flights from Austin (AUS) to Liberia, Costa Rica (LIR) for $218, NONSTOP. Flights February to April. Departures on Tuesday, Thursday, and Saturday. Very few extended weekends available. Origin/Destination reversible. Click for more details and booking links Nonstop Flights: Austin to/from Liberia, Costa Rica $218 r/t [February-April] â American Airlines . | 