We went two years ago and it cost us roughly 9 tl each way from
Marmaris to Ortaca, it is2.50tl from
Icmeler to Marmaris and about the same from Ortacato to Dalyan. The bus goes from the bus station at the top end of Marmaris and they overlap so one is waiting at the next change over, this is the same bus that will take you to Fethiye and goes every 30mins. Only a guide but might help