I bought Turkish sim for 34 mil inc 100 units. One text message = 3 units. 34 mil was about £14.00. I bought it in Fethiye opposite the mosque. The phone shops there check if your phone will take the sim and set it all up for you. When I needed more units, I took it back to them and they did everything for me. It is much cheaper for local calls, also if anyone calls you from the uk, your turkish phone doesn't get charged as is the case with your normal phone.
Christine