There are government defined figures for estimating buildings costs depending on the type of property - normal tugla, steel frame etc etc. I have the link on my uk computer (most useful!) and I'm pretty sure that Land of Lights, the Fethiye newspaper publish a list every year, or at least they used to. The figures are updated each year in line with inflation but the latest figures I can find are 2007.
Depending on the type of property I also add costs for clearance of land in as these can really mount up if you have to do a total rebuild, so it needs to be a good few thousand for that.