The island is a 15-minute boat trip from Tairua or Pauanui or a 30-minute helicopter journey from South Auckland's Ardmore Airport.
Brakenridge said the Needhams, a farming family originally from South Auckland, had owned the property for about 45 years.
The Thames-Coromandel District Council lists the 217ha property as having a rating valuation of $5.5 million. Expectations are that it could fetch about $7.5 million but Mr Brakenridge said that it was open for offers.
International real estate specialists Vladi Private Islands has advertised a 1.7ha slice of the island in two lots for $1.85 million, saying they are both building sites with panoramic views.
Rare opportunity
• 217ha of the 224ha Slipper Island, or Whakahau, is for sale. It has its own airstrip
• 6 houses: four holiday bungalow-style guest chalets and two residences.
• 15 minute boat trip from Tairua or Pauanui or a 30-minute helicopter journey from Ardmore Airport.