Key Points:

The buyer of a North Shore house that was auctioned with a $1 reserve has been unable to find the vendor.

The designer home in Browns Bay was sold by auction at Labour weekend for $685,000, about two-thirds of its advertised $1.03 million independent valuation.

Colin Boot, who placed the winning bid, told the Weekend Herald yesterday that he had since tried to put a $69,800 deposit on the house but could not contact the owner.

"He won't take the deposit ... I was going to give him cash in a briefcase."

Mr Boot, from Christchurch, said he could not get hold of Jinjang Liu, also known as Jason Liu.

Just after he put in the winning bid, Mr Boot signed a document handed to him by Mr Liu. He was then distracted by media interviews. "I was swept away by the moment. By the time I turned around he'd gone."

Mr Boot is frustrated he does not have a copy of what he signed but has taken legal advice and placed a caveat on the property meaning no one can do anything with it in the meantime.

He now fears the auction may not have been above board. "No real estate agent was involved, no advertising company," he said. "It was only listed on Trade Me ... and a poster outside the house and about 100 flyers ... It's embarrassing to everybody."

The Weekend Herald repeatedly rang Mr Liu's cellphone yesterday but the calls went straight to a voice message, and he did not reply to a message to contact the newspaper.

The four-bedroom house with sea views at 7 Paterson Mews attracted huge attention, with 46 registered bidders and even more onlookers. The $1 reserve implied the house had to sell.

Auctioneer Alastair Beer told the Herald yesterday that his job was only to run the auction on the day.

He confirmed it had been a private sale, with no real-estate agency involved, but did not want to comment on the outcome.

Mr Beer had earlier told the Herald a reputable company had valued the house at $1.03 million within the past 12 months. Quotable Value last month put the price at $840,000, but Mr Beer had said QV figures and independent valuations always differed.

At time of sale Mr Liu, who had not wanted to be named or photographed, told the Herald he was satisfied with the price although it was "a bit low".

Bob Eades, an Auckland property lawyer, said if the document signed by Mr Boot was a standard sales form it would be a binding contract. But Mr Eades said even if it wasn't a set form it could still be binding if it included the property description, the price and a settlement date.

He said it was possible the price was too low to meet debts on the property and the vendor's bank had pulled the plug on the sale. While the vendor could be sued by the would-be purchaser, there was no point if he had no money.