Just booked January 2013 Melb to Denpasar (direct) for $422.74 return for 2 people. Honestly thought it was a mistake, these prices are insane.
I entered many different dates and got lucky with these tickets.
Once I booked, I reentred the same dates and the total was $1,400.00 odd for 2 tickets.
Have a try, I also entered dates in December (early) and the costs were the same $422.74 return for two. Tried lots of dates for Nov, Dec, Jan & Feb and heaps were over $1,000 for 2.
Thought is was worth mentioning.