BKK is certainly a favourite QR destination for low fares - I did it from VCE earlier this year during the sale for a touch over £1k, positioning on BA from LGW the night before and having the day wandering around the city before catching the evening flight to DOH (hotels are reasonable out of the city, taxis are extortionate, but left luggage costs by the bus station where the airport service leaves from are very cheap, so it all sort of balances).
If you're prepared to wait, and can be flexible in positioning City, then you might save a little bit more and potentially get a QR widebody which I gather is a much better experience than some of the A320 series which have variable business class seats.