Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Thailand to Bandung as you normally would.
Bandung Husein Sastranegara (BDO), located 4.4 km from the city centre, is the airport you fly into when you book flights from Thailand to Bandung.
Yes, there are multiple flights from Thailand to Bandung for under ฿12,200. The cheapest flight booked recently is on Multiple Airlines for just ฿12,175, but on average you can expect to pay ฿14,444.