Now the new owners have on-sold for $1,205,000 - despite doing little work on the property - giving them a 16-month profit of $454,000 - about $940 a day.
"I'm still in shock," Mr Duncan said after learning how much his old property fetched. "It's just disbelief.
"It was an 80s house, three-bedroom do-up. Where is the market going? God help New Zealand."
The Weekend Herald has analysed annual house sale figures and compared them to wages earned in the country's 12 regional council areas to calculate whether people's homes are earning them more than they get from working.
In Auckland, the average house earned nearly $230 a day in the past year - about twice the average worker's pay. That's about the same as an entry-level doctor or high school head of department with responsibility for 10 teaching staff.
The one-bathroom Browns Bay property has a CV of just $800,000 and comes with a garage and carport. It sits on 1043sq m freehold and is zoned for Rangitoto College.
Barfoot & Thompson agent Eve Huang said though the vendors had done little work on the property, they had obtained resource consent for the large section to be subdivided into two lots, which increased its value.
The new owner was likely to demolish the existing dwelling and build two new houses.
Ms Huang was not surprised by the $1,205,000 price; she said it reflected the intense demand for land.
"Anything with the potential to subdivide has a huge capital gain. They're buying the future, they're buying the land."
Mr Duncan said he couldn't believe how the market had taken off, and blamed foreign buyers with deep pockets for what was fast becoming a housing crisis.
"Every auction you go to, if they want it they just don't give up. It's a bottomless pit. It just doesn't seem right. We're going to end up with a generation that don't own property."
The Reserve Bank waded into the debate this week, warning that housing-market imbalances "are presenting an increasing risk to financial and economic stability".
Deputy Governor Grant Spencer urged the Government to take another look at a capital gains tax on property investors to dampen demand, allow higher-density development and cut red tape for planning consents to address the over-heated Auckland market.
House price inflation had risen by 17 per cent in the past year, and the gap between incomes and prices was widening, especially in Auckland.
And yesterday, the Chief Human Rights Commissioner added his voice to those calling for drastic action.
David Rutherford called for a cross-party political accord to tackle the "very serious" issue of ensuring adequate housing - which he said was a human right and binding legal obligation on the state.
