SalamAir, Oman Air and Flydubai fly from Muscat to Salalah hourly. Alternatively, Mwasalat operates a bus from Muscat to Salalah 3 times a day. Tickets cost $19 - $28 and the journey takes 12 h 30 min.
From Muscat taxi to Muscat airport then fly to Salalah airport. 1 h 50 min $198. From Muscat taxi to Muscat International Airport then bus to Salalah. 12 h 41 min $42. From Muscat drive to Salalah. 11 h 31 min $57.