Here's the reply from my friends in Datca:-
Datça is not a cheap place, Tuna pensiyon, is OK, our villa is on a hotel site, Marphe Otel, but might be too expensive. It's very easy to drive to Datça, just follow the signs to Marmaris, and there are plenty of signs from there, there is only one road to Datça, over the mountains, with some fabulous views.