A few people asked about hops across the ditch after the last post, so I ran the scan again tonight. AKL/WLG/CHC/ZQN against SYD/MEL/BNE/OOL, dates through August and September. Jetstar has quietly flattened trans-Tasman fares and nearly everything cheap is direct:
Auckland → Gold Coast, 8 or 22 Sep: ~NZ$231 (Jetstar, direct, 3h35)
Auckland → Brisbane, any date I checked: ~NZ$242 (Jetstar, direct, 3h50)
Auckland → Melbourne, 11/25 Aug or 22 Sep: ~NZ$246 (Jetstar, direct, 4h05)
Christchurch → Melbourne, late Aug to Sep: ~NZ$250 (Jetstar, direct, 3h45)
Auckland → Sydney, 25 Aug onwards: ~NZ$255 (Jetstar, direct, 3h40)
Queenstown → Sydney, 22 Sep: ~NZ$276 (Jetstar, direct, 3h15)
The Auckland → Brisbane one is the weird one. Same NZ$242 on every single date I sampled across six weeks, so you can basically pick your day. For everything else the date does the heavy lifting: the same Christchurch → Gold Coast leg was NZ$405 on 11 Aug and NZ$250 on 22 Sep in the same scan.
Rather fly full-service? Air NZ wasn't miles off on some legs. CHC→SYD came back at ~NZ$323 and WLG→SYD at ~NZ$331, both direct.
The link goes to the Auckland → Brisbane search with everything prefilled and it runs the search automatically, prices show in NZD. Change the From city or destination on the same page for the other routes. Full disclosure: it's my site, it's free, no signup, and it makes money off booking links like every flight comparison site.
Usual caveats: one-way fares, hand luggage only pricing (it's Jetstar, bags and seats are extra), prices converted from AUD so expect a couple of dollars' movement at checkout, and fares at this level tend to quietly disappear. All were live when I searched tonight.