Air Asia sale, lots of fares across Asia/Oceania from US$3 one way.
For example: KUL (Kuala Lumpur) to PEN (Penang) return from $6.
Struggling to find expiry date, but will update if found.
Need to join their BIG membership program (free) to get the very cheap ones.
Edit, another example:
Kuala Lumpur to Johor Bahru - AUD$6.30 (non Member) = https://www.airasia.com/booking/select/en/gb/KUL/JHB/2019-09…
Kuala Lumpur to Kota Bahru - $AUD6.30 (non Member) = https://www.airasia.com/booking/select/en/gb/KUL/KBR/2019-09…
Whod bother to join for $2-3…