| Cheap Flights: Austin to Barcelona or Madrid $366-$371 r/t [September-October] â Delta / Virgin Atlantic Delta and Virgin Atlantic have round-trip flights from Austin (AUS) to Barcelona or Madrid (BCN, MAD) for $366-$371 with a connection. Flights September to October. 7-day minimum stay required. Click for more details and booking links Cheap Flights: Austin to Barcelona or Madrid $366-$371 r/t [September-October] â Delta / Virgin Atlantic . | 