What is the best way to travel that is both economical and efficient?
For the trip I had planned (though in reverse) would be to visit Ephesus out of Kusadasi, then Bus to Izmir (nearby) and from Izmir, fly to Istanbul. Try Atlasjet, Onurair, and Pegasus, all Turkish Budgets. Buses are also cheap and supposedly very nice, but it is a long ride.
lessa, bus is good as my trip, while long and at night, had amazing fellow travelers. a nigerian footballer was heading to his turkish team a talked of his home, and thoughts about living in his new town. pair of swedish women were trekking across europe for a year, and were just halfway. the local turks were friendly and shared food and learned enlish along the way. arrived early am for a great fulll day in kusadasi
The bus will take about 10 hours from Izmir to Istanbul, so you will either have an all night bus ride (which, as was pointed out, can be an interesting if exhausting experience) or you can take a 45 minute flight. The bus is about one third the cost, but will cost you a travel day, since even if you take the all night bus you will likely nap through most of your arrival day in Istanbul.
So, what is in shorter supply for you, time or cash?