One fee-free date change available with fare difference, see terms here . Travel period is mid-July to October but excluding school holidays.
According to this news.com.au article:
Jetstar has released 10,000 one-way fares for $19, servicing 22 routes including Melbourne to Sydney, Sydney to Gold Coast, Melbourne to Byron Bay (Ballina), Brisbane to Whitsunday Coast (Proserpine) and Adelaide to Cairns.
Other fares available for sale from 9.00am Friday until Monday night, unless sold prior, is a $49 flight from Brisbane to Mackay as well as $79 from Sydney to Hamilton Island and Brisbane to Darwin…
$19 FLIGHTS
[Update: flights are in both directions]
- Adelaide – Melbourne 21 July – 17 Sept, 7 Oct – 31 Oct
- Adelaide – Sydney 21 July – 17 Sept, 7 Oct – 31 Oct
- Adelaide – Cairns 13 August – 17 Sept, 7 Oct – 31 Oct
- Melbourne (Avalon) – Gold Coast 15 July – 10 Sept, 7 Oct – 31 Oct
- Melbourne (Avalon) – Sydney 21 July – 17 Sept 6 Oct – 31 Oct
- Brisbane – Sydney 21 July – 17 Sept, 6 Oct – 31 Oct
- Brisbane – Proserpine 21 July – 17 Sept, 6 Oct – 31 Oct
- Brisbane – Townsville 21 July – 17 Sept, 6 Oct – 31 Oct
- Melbourne – Ballina 14 July – 17 Sept, 6 Oct – 31 Oct
- Sydney – Ballina 21 July – 17 Sept, 6 Oct – 31 Oct
- Melbourne – Cairns 14 July – 17 Sept, 6 Oct – 31 Oct
- Cairns – Gold Coast 6 Oct – 31 Oct
- Sydney – Cairns 21 July – 17 Sept, 6 Oct – 31 Oct
- Melbourne – Sunshine Coast 14 July – 24 Sept, 13 Oct – 31 Oct
- Sydney – Sunshine Coast 16 July – 24 Sept, 13 Oct – 31 Oct
- Melbourne – Newcastle 21 July – 17 Sept, 6 Oct – 31 Oct
- Melbourne – Gold Coast 14 July – 17 Sept, 6 Oct – 31 Oct
- Melbourne – Sydney 4 August – 17 Sept, 6 Oct – 31 Oct
- Newcastle – Gold Coast 21 July – 17 Sept, 6 Oct – 31 Oct
- Sydney – Proserpine 6 Oct – 31 Oct
- Sydney – Townsville 21 July – 17 Sep, 6 Oct – 31 Oct
- Sydney – Gold Coast 21 July – 24 Sept, 13 Oct – 31 Oct
So it looks like they have designed it so you can't get cheap flights both ways for the majority of routes. Good one.