All major airports run some sort of bus or coach service from the airport to town.
I travelled all over Europe on business and NEVER had to take a taxi from local airport to the town centre, there was always some sort of bus or coach service.
Ask at information when you get there, or look on the web site for the airport.
Like VHG says, check which airport, but even the furthest out (Schoenbrunn? Schoen-something) one has a direct train that is very affordable, with a covered walkway staright from arrivals to the train station.