If you know where to go, where to buy and eat, you can make your trip cheaper than you expect. If you have a friend or if you have good contacts in Turkey, you can get a lot of benefits and can reduce your costs considerably. Do not hesitate to ask questions to the companies or individuals you meet. Turks love to help foreigners.
Most expensive city is Istanbul.
Smaller cities and towns and the regions further away from tourist destinations are cheapest. There is a meter in the taxis that measure the length of travel. Waiting in the blocked traffic is not measured. Air flight to most of the big cities and the regions is possible. Check Turkish Airlines for the recent prices.