Using the Jetstar Australia to NZ sale in reverse, there are some great prices to Australia. I've tried to find the best ones available:
Summary:
Auckland - Brisbane return (9 Aug 26 - 31 May 27) from $526 return
Auckland - Gold Coast return (13 Aug 26 - 29 Aug 27) from $502 return
Auckland - Melbourne (Tullamarine) return (2 Nov 26 - 31 May 27) from $556 return
Auckland - Sunshine Coast return (7 Aug 26 - 23 Oct 26) from $518 return
Auckland - Sydney (Kingsford Smith) return (27 Oct 26 - 31 May 27) from $524 return
Christchurch - Gold Coast return (15 Feb 27 - 31 May 27) from $551 return
Christchurch - Melbourne (Tullamarine) return (8 Nov 26 - 13 May 27) from $566 return
Christchurch - Sydney (Kingsford Smith) return (26 Oct 26 - 17 Mar 27) from $550 return
Dunedin - Gold Coast return (29 Aug 26 - 29 May 27) from $467 return
Hamilton - Gold Coast return (2 Sep 26 - 31 May 27) from $501 return
Hamilton - Sydney (Kingsford Smith) return (3 Sep 26 - 29 May 27) from $434 return
Queenstown - Brisbane return (28 Sep 26 - 10 Oct 26) from $558 return
Queenstown - Gold Coast return (12 Oct 26 - 29 May 27) from $605 return
Queenstown - Melbourne (Tullamarine) return (8 Nov 26 - 30 May 27) from $559 return
Queenstown - Sydney (Kingsford Smith) return (17 Nov 26 - 31 May 27) from $498 return
Wellington - Gold Coast return (10 Feb 27 - 29 May 27) from $543 return
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Also consider having a look at the current best found deals by city - Auckland, Christchurch, Dunedin, Hamilton, Queenstown, Wellington.