Look out for someone else's dream home after they've already done the hard work.

A young family, with children aged 4 and 2, who had recently emigrated from England, couldn't believe their luck on Saturday.

Lee, who works in finance, and Suzanne, a management consultant, picked up an Alex Roth designer pad in Coogee for below replacement cost, after just two months of searching Sydney's eastern beachside suburbs. And there's even a view of the beach from the master bedroom.

"When we saw the house, we just thought 'wow, it's a great design, amazing construction with no expense spared'," Lee said.

"It's amazing how they've managed to maximise the space and there's tonnes of light."

There was just one other couple competing at the auction for the five-bedroom, three-bathroom house at 145 Arden Street, Coogee, and Lee and Suzanne picked it up for $3.57 million. The vendors had knocked down a 1980s home for which they'd paid $1.4 million in 2012 to build the new designer palace.

It was one of 360 auctions held in Sydney on Saturday, with 229 of the results in by Saturday evening. Domain Group put the clearance rate at 67.7 per cent.

"It's the third week in a row that the clearance rate has fallen and the weakest result of the year," Domain Group chief economist Dr Andrew Wilson said.

Bidding for the Coogee property stalled at $3.55 million. After McGrath agents Adrian Bo and Nick Lennan consulted with their vendors, the couple lifted their bid by $20,000 and the property was on the market and quickly sold.

Lee thought it was a fair deal. "The owners paid $1.4 million for the original house and their construction costs must have been close to $2 million, so they haven't made a huge amount of money on it," he said.

Although it appeared that the vendors had to adjust their reserve slightly during negotiations, Mr Bo said it was a good price. He said there was plenty of demand for these types of properties in the eastern suburbs and a shortage of quality stock.

"There are a lot of buyers looking at this price level after upgrading from their semis, which had been selling for about $1.5 million but they're now either side of $2 million," he said.

"And those sort of prices are catapulting these buyers' budgets into the $3 million-plus range."

Meanwhile in the Southern Highlands no bidders wanted to part with about $7 million for former Liberal leader John Hewson's six-bedroom estate Invergowrie at 74 Bundanoon Road, Exeter, on Saturday.

A crowd of 90-plus gathered in the park-like grounds, but many were sightseers and locals taking the opportunity to view the famed Sorensen gardens and the grand home built in 1936 for Cecil Hodgkins.

Two parties registered but the home passed in without a bid.

Michael Maloney, of Richardson & Wrench Bowral, said he was confident of getting a genuine bid on the table from the four parties who have expressed interest at about $7 million.

"We would have liked a sale under the hammer but that's not always the way it happens," Mr Maloney said. "These are big decisions when you have a property of this magnitude."