| Cheap Flights: San Antonio or Austin to Key West $235 r/t [September-November] â Delta / United Delta and United have round-trip flights from San Antonio or Austin (SAT/AUS) to Key West (EYW) for $235 with a connection. Flights September to November. No Thursday departures. Extended weekends available. Click for more details and booking links Cheap Flights: San Antonio or Austin to Key West $235 r/t [September-November] â Delta / United . | 