The Cebu South Bus Terminal (CSBT) is your best option to reach Moalboal on a budget. Take a bus from Mactan Airport (Cebu Airport) to SM City Cebu (Mall) and then from there order a Grab to South Bus Terminal Cebu (most affordable option). Go to the ticket station in the terminal and tell them you'd like to take a bus to Moalboal. Once you have a ticket lookout for a bus called "Bato via Barili", "Badian" or "Moalboal". The total cost of the whole journey from the airport to Moalboal will be about 17$.