The Turkish bus system is comprehensive and you can get about anywhere from everywhere. Better spend a few more liras and you will have an unforgettable journey. Ulusoy has buses with seats that resemble business class in airplanes. There are also other bus companies, including Kamil Koc, Truva and Varan. Some companies have an onboard WLAN.
The termınal in Antalya is separated in two buildings. The larger building obviously houses the long distance bus routes, and the smaller building to the left (west) serves for shorter distance routes including Serik, Manavgat, Side, and Fethiye.
Fares are low. Simply show up at the bus station (“otogar”) and announce your destination. From most cities, there are an overnight bus options (with Antalya). There are regular buses destined for Anatalya that run along the coastal roads and stop at tourist towns such as Kas and Fethiye.