"This is one attempt to make land and homes more affordable."
Stanley said the couple would live in the centre block with their family and sell the other two for $300,000 and $315,000.
Coles said as part of the sale and purchase agreement potential buyers would be asked to sign a memorandum of understanding that set out values and shared commitments.
"The values reflect people's desire for neighbourliness and treating the land well."
He said the commitments included intentions toward being poison-free, not surrounding a property with high fences, and meeting up and sharing some resources.
"It's a gentleman's agreement about the way we want to share the subdivision to maximise the community, sustainability and affordability benefits.
"At the end of the day, though, owners have the autonomy to decide what to do on their own property.
"We're putting our faith in goodwill rather than the legal process."
Stanley said they currently lived in the Quaker Settlement.
"There are some massive benefits. I love walking outside and seeing your neighbours."
Coles said they chose the site at Flemington Rd because of the space and sense of tranquillity, and because it was within biking distance from Whanganui city amenities.