About $3.9 million of taxpayers' money has been spent investigating, prosecuting and defending the 18 people arrested in the Urewera raids.
The bill is set to rise even higher if a second trial on organised crime charges is sought.
Fresh figures released to the Herald show more than $1.16 million in legal aid has been paid to defence lawyers for the four who stood trial in the High Court at Auckland this year. Just over $93,182 has been claimed for the five-week trial which ended in March.
But the total bill for Tame Iti, Urs Signer, Te Rangikaiwhiria Kemara and Emily Bailey could be higher, as not all the legal aid invoices have been filed to the Ministry of Justice.
The legal aid bill for a fifth defendant, Tuhoe Lambert, was $132,692. He died before the trial started.
A further $1.63 million has been paid to the lawyers of 13 other accused whose charges from the October 2007 raids were dropped last year, when the Supreme Court ruled the evidence against them was gathered unlawfully.
Figures released by the Crown Law Office show nearly $119,457 was charged for the time of the three prosecutors for the trial. This is on top of the $322,412 spent on prosecutors to work on the case up until the trial started in mid-February. The police have provided an "aggregate figure" of $500,462.
The case was taken through the District Court, High Court, Court of Appeal and the Supreme Court, which increased the total cost.
The total of $3.88 million makes it one of the country's most expensive cases. In terms of legal aid paid, only the $3.3 million paid in the David Bain trials and appeals is higher.
The Crown could seek a second trial for Iti, Signer, Kemara and Bailey after the jury was unable to reach a verdict on the charge of participating in an organised crime group. That decision will be announced soon.
The four will be sentenced on May 24 on the firearms charges the jury found them guilty of.