I've always bought my perfume at the UK airport i'm using - they usually have some good deals on, so have never really looked in resort but I think there are some chemists in
Marmaris selling genuine perfumes...
If you're going to buy perfume in Turkey my advice would be to buy it
Dalaman Airport to guarantee it's the real thing - having said that there doesn't seem to be a huge range and I really don't think it's much cheaper than you would pay in the Duty Free shops here....
Certainly what you buy in shops and bazaars will be (very good) "genuine fakes" as the Turks like to call them - but the scent only lasts about an hour....
Mazz