i have used the airport bus and the driver took us over to the international departures,it leaves from the autogar now and stops outside areis hotel.i think the price might be 20ytl each,but as its just been said it only goes when the internal flights are on and thats usualy morning after 5.30 or early evening.its ok if you dont mind hanging around the airport for a few extra hours.take plenty food and drink if you decide to wait around.