We did this in May, went to Fethiye otogar asked to go to Dalyan. Dolmus/bus seemed to go every 30 minutes to Ortaca, dropped us right beside bus to Dalyan. If you have a Mugla/Kent bus card you can use that on the whole journey, can't remember the cost now but not very much like a lot of journeys in Turkey. We really enjoyed our trip there, so much that we hope to go again in September.