If you are traveling from the Netherlands or Germany (or another country) we advise you to fly to Izmir Adnan Menderes Airport. There are a couple of options to get to your final destination in Kuşadası but the two that we recommend are:

1) Take a taxi, there are websites that lets you reserve a taxi ahead of time so that you don't have to worry about it at the airport (although you can also get a taxi there). The trip will take about 1 hour and should cost you between 50 and 75 euro. (potential website: https://www.suntransfers.com/izmir-airport)

2) Rent a car, it will take you again 1 hour but you can rent cars similarly to other countries and they even have the common renting companies available like Sixt and EuropCar. The benefit is that you will have the car available for you during your stay and it will be easier to get around if you want to do some sightseeing in the area.

3) Shuttle bus. It will take you about 90 minutes to get to Kusadasi which is a bit longer, and you do have to wait for the shuttle which leaves about every hour, but it is the cheapest option costing only ~9 euros. More info can be found on: https://havas.net/en/bus-services