I worked with an architect/builder and what memory serves me from his conversations with the Tapu office is:-
The Tapu office are dealing with the building of the property, the government set out each year the cost to build a property, this ranges from (for example) e,d,c,b,a. A is the unusual in as much that it is used for luxurious properties, using the very best materials etc.. not something Fethiye can boast. the cost is so much Lira per square metre, when they cost at the Tapu office they do not deal with the land the property is sited on.
This may sound strange, yet this is how it was explained to me, you could have purchased a piece of land some 10-15 years ago, now you would like to build a property, it is the cost of the property that is registered, should it fall down you still own the land. Some where in there is sense, just don't ask me.
I know the cost of a property on this forum, the owners paid £90k, the build receipt was for £16k (at the exchange rate that time) it was not my place to argue at the time. we laugh and joke that when we purchase think of a number, half it and add 10% in Turkey.
In 2004 I was sat in a bank in Fethiye, I was waiting to be seen, in the mean time the clerk was dealing with a couple of Brits who had purchase in Ovacik, they wanted to insure the building and contents, the man had purchased his villa for £120k the clerk without flinching told him that they could not insure for that amount, it was too much, she phoned someone, she looked at the Tapu, after putting the phone down she said the most they could offer was ??k, the chap had a fit!!! he turned to his wife and said "see I knew we were ripped off" now why the complaining, he was happy with his villa, he paid the price, the cost to rebuild was there and he still owned the land.
Every year the government list the build price/cost, it used to be in the LOL, Some Turkish business person or Tapu office will be able to provide you with a copy.
Everything is for sale, and only worth what someone is willing to pay.