There is probably loads of stuff on here about TAPU.
When your army clearance is applied for (which you need to get your TAPU), you need to provide certain maps from the council, so you have to pay 'map money'- when we applied for our army clearance last Oct. this was £210 for Uzumlu (Fethiye/Calis is apparently much more expensive).
Once the army clearance is through, the TAPU can the be obtained - at this point you pay 3% of the declared value of the property and a registration fee of £100.
So I expect round about £500 is a good guide.
I don't really know at what stage you should apply for TAPU if your villa is new build as yours. Maybe someone else can help. In our case our contract said we were to pay the last payment to the vendor on transfer of the TAPU - so I would have thought yours would be similar. Hence you would only pay the last payment if you were entirely happy with the build.