A lot cheaper than you are used to
Not sure what differences in prices will be this year from last but typically
a pint of Efes last year was around 3 Lira
English Breakfast (if you want that sort of thing) 5 Lira
Turkish Breakfast 7 Lira
The most expensive meal we had (and yes we did push the boat out on that night) including drinks was 70 Lira
A usual evening meal for two was around 20 to 30 Lira with drinks
Trips out are equally inexpensive - a day on the boat to Turtle Island then on to the Mud Baths at Dalyan and return with all boats, transfers to and from the hotel, a meal on the boat out (drinks were extra), entry to the mud baths and the services of a guide for the day cost a total of 50 Lira.
At the time, the exchange rate was roughly 2.5 Lira to the £. I've just had a look it is currently roughly 2.3 Lira to the £.
The only really expensive thing we found was petrol (we always hire a car) at the equivalent of £1-40 a litre when it was under a pound in the uk. However, I have since been told that I should've asked for an LPG car - gas is much cheaper.
Hope that helps
Dave