Ian it will probably cost about the same if you take the test, as you will still have to do everything except your license translation to get the Turkish license, i.e. medical, blood test, fingerprints, criminal record check, buy the correct folder to put it all in, etc. and if you fail the test!!!! easier to just translate your license etc.
The license cost is the same for the turks, except they don't have to translate a license, which is not the main cost, the license is.