Eindhoven Airport handles a steady stream of budget flights (Ryanair, Transavia, Wizz Air) from across Europe. The airport is about 8 km west of the centre; bus 400 or 401 runs to the central station in 20 minutes.
If you fly into Amsterdam Schiphol, take a direct intercity train to Eindhoven Centraal (about 1 hour 20 minutes). From Rotterdam, the train takes roughly 1 hour with a change at Breda. Tour buses and long-distance coaches arrive at the central station, which is a short walk from the city centre.