Looking to book a flight from Ottawa - Queenstown - Gold Coast - Ottawa for end of July/beginning of August.

Saw the fare on the air new zealand site for ~$1800 pp, which is there "sweet deal" fare. Thing is I found a similar price a couple days ago, only to have the fare go up the next day, but then yesterday the fare was back down... but currently it's up to ~$2300.

Anyone have any info on these types of seats? Do they release more as they're sold? Or once they're gone it's gone? I'm kicking myself for not jumping on this when I saw it the 2nd time. Hoping the lower fare will come back....