Gareth Morgan has offered to pay the difference for a pristine beach in the Abel Tasman, currently up for sale by its owner and the subject of a popular crowdfunding campaign.
The New Zealand businessman and philanthropist said he doesn't agree that the government should spend taxpayers' money on the bid.
He proposed the offer on his website this afternoon.
"I will make up the difference between the crowd-funding amount and the tender offer of $2m," Mr Morgan wrote.
"I will guarantee that the public have access to the same extent that the current owner has kindly bestowed.
"But I will go further than that. I will undertake to give the property to DOC once my family has finished enjoying it.
"But I expect something in return – I want to use the property for my own private benefit meanwhile, just as the current owner does."
The target of $2 million is looking closer to a reality today, with contributions sitting at $1.4 million at time of writing - 21,439 donors have given an average donation and the Givealittle campaign closes in five days.
Labour leader Andrew Little this morning told TVNZ's Breakfast programme he has personally contributed to the campaign, and called on the government to meet the shortfall if needed.
He said it would be especially meaningful around Waitangi Day, "which is all about our national identity".
"I thought ... we spent $26 million on a flag ... why not a million or $800 thousand on making sure we secure this beach for future generations?"
The beach owner has riparian rights, which means that if a private buyer were to own it, they could potentially limit public access.
It is also reportedly generating interest among overseas buyers.