Syd, Melb, Adelaide, Brissy to Bangkok $891 with British Airways
The base cattle class flight usually costs you upwards of $1000 return. To get the discounted price you need to be a member of the Thailand Tourism Authority - which is just a normal website sign up / email address harvesting process.
There's a bunch of dates in there through to March 2009 but booking closes on 30th August. What I'd love to find now is a cashback link to the main british airways site. We carry one for British Airways Holidays but I suspect its a different link and they wouldnt pay cashback on it.