I have flown AirAsia quite a bit. Its been pretty reliable and cheap!
Its about au$100 for international flights.
I usually pay the extra au$10 for a selected seat and don't forget to pay for the right luggage weight when you book. Its a lot cheaper that excesss at check in.
(In country flights are much cheaper au$10 to $50 ish in Malaysia and Thailand) about 10 years ago