The helicopters have been running 12 hours a day and with an hourly bill of $2000, their daily cost was believed to be in excess of $500,000.
The forestry industry has been the worst-hit by the fires, losing an estimated 1900 hectares and having to shut down its operations within the fire perimeter.
That has temporarily put 240 contractors out of work and closed two sawmills. Forestry Minister Shane Jones said the estimated cost of lost productivity was $2 million a day - or around $14 million so far.
Farmers in the region have also had to put a halt to any use of equipment out of concern that any sparks could restart fires in the rain-starved region.
Insurance claims will push the bill much higher. In the Port Hills, nearly $18m was paid out, around $10m of which was for house and contents insurance.
In Nelson, just one house has been confirmed as destroyed. However, the area of land affected is far greater than in Christchurch.
The costs in major fires are divided between a range of agencies and authorities, including the local council.
The New Zealand Defence Force has contributed 220 personnel and two aircraft to the firefight, though those costs are covered by the NZDF's own budget.
The Government has so far contributed $120,000 in support for the region, and the Ministry of Social Development has been providing hardship support and grants.
Nelson fires (Feb 6-ongoing)
Hectares: 2300
Duration: 8 days (so far)
Homes destroyed: 1
Homes evacuated: 1100
Port Hills fires (Feb 2017)
Deaths: 1
Hectares: 1645
Duration: 15 days (66 days until fully extinguished)
Homes destroyed: 9 (+ 5 damaged)
Homes evacuated: 450