Upvote:1
Flight prices, especially those between the major eastern capitals (Sydney, Brisbane, Melbourne), are pretty stable in Australia.
In general there are two pricing tiers used by Australian airlines - the "deals" and the standard. There's a certain number in the deal bucket and everything else goes into the standard bucket.
If there are available tickets in the cheaper bucket it's worth booking ASAP. If there's none left the standard flight prices don't tend to increase significantly. Indeed you'll find prices vary more significantly across the day rather than between days - first thing in the morning is the cheapest.
If you monitor the prices you might get cheaper sale prices if you're flying off peak times (no weeknights, no weekends) but the difference often isn't more than the difference between the "deal" and "standard" options.
Upvote:1
Yes, prices for Australian domestic flights tend to increase as the departure date approaches. You can trivially confirm this with a local booking engine like Webjet, and here's a snapshot of their best available SYD-MEL fares for the next few weeks:
Note how all flights in the next 4 days are >$220, the following 4 are in the $150-200 range, and only beyond that do you see any flights in the sub-$100 range.
Also, there's nothing particularly Australian about this phenomenon, it applies to all modern airline pricing. See this epic answer for much more detail.