"We're going to make a pretty firm offer and basically it will be take it or leave," David Napoli, Chairman of the Bali Peace Park Association, told AAP.

Negotiations with the owners of the former Sari Club, where 88 Australians were among the dead, have been arduous and ongoing over many years.

"Our offer is well into the millions of Australian dollars," he said. "I'm hoping we'll be able to put the offer to the owner by the end of the week."

He said negotiations were being led by an Indonesian woman, Lila Tania, representing developer Sukamto Tjia and his family who control the site in the famous Kuta nightclub strip.

The publicity-shy family reportedly backed out of an earlier deal of $A4.9 million for the 700 square metre plot, demanding a further $A9 million 'in compensation'. But Napoli, currently in Bali, added that "a lot of "fantasy figures" had been bandied about.

The Australian, Indonesian and Balinese governments have supported the proposal along with senior officials like Made Mangku Pastika, the general who led investigations into the attacks by the al-Qaeda-linked terror group Jemaah Islamiyah.

Prime Minister Scott Morrison threw his political weight behind survivors before the May election, saying he was "deeply distressed" that planning approval for a five-story development of the former Sari Club had been granted.

Napoli said that approval had sharply increased the value of the plot which was initially valued at about $A500,000. He declined to outline specific figures but added "it's a very generous offer".

He said two approaches for a peace park could be made to challenge radical thinking while serving as a memorial for survivors and the wider public.

The park, if the sale goes through, is expected to provide a peaceful sanctuary of gardens and nature to promote reflection. This could include story pods from victims' families and survivors telling their stories of how the night of October 12, 2002, had changed their lives forever.

Australian Associated Press