Philanthropist Gareth Morgan says he will have spent $600,000 on his Treaty of Waitangi campaign by the end of the year.
He came up with the figure in response to claims he's pushing the cause to sell his book, Are We There Yet?.
"It cost me a hell of a lot of money to do the five years' work," he said. "By the time we've finished this year I would say this project would be up in the $600,000s."
The estimated cost doesn't include Dr Morgan's time, which has included extensive meetings, speaking and writing.
Dr Morgan has spoken plainly of his desire to see te reo become compulsory in schools, an Upper House for Parliament of which half was Maori and other steps in an attempt to meet Treaty obligations. A large portion of the money went into the research, he said.