Mooring fees in Turkey differ depending on the location of the marina and the season. The marinas in Aegean Sea are generally more expensive than East Mediterranean marinas in Turkey. During summer period, the cheapest daily mooring fee for 12 meter (40 feet) yacht is around 22 Euros and the most expensive is around 85 Euros. Sure these prices change according to weekly, monthly stays. So the best way is to contact with marinas and ask directly.
Turkish Marinas contact information
Marmara Sea Region