A beautifully renovated but otherwise unremarkable house in Arncliffe attracted as many as 19 bidders at Saturday's auction, many of whom had already missed out at previous auctions.

The fierce competition pushed the price up to A$1.7 million, well above the A$1.35 million projected when it was first listed.

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The property was one of a number of auctions this week that attracted more than 10 bidders - the market is usually slower due to the unpopularity of winter sales.

To put this in perspective, this time last year the Reserve Bank was in the early stages of its interest rate hiking cycle, and a typical auction would have attracted around two to five registered bidders.

The high number of bidders at the Arncliffe auction encouraged interested parties to make bold bids.

The eventual buyers reportedly adopted an aggressive strategy, countering the small rate hikes with larger increments - known in the real estate industry as "knockout bids."

Auctioneer Perry Edmondson Clark said the strategy worked." You can tell from the start that he wants it. He said, "You could tell from the beginning that he wanted the land and his bid was very strong and bold." Some of the other bidders were also very firm. They could see how many other bidders were paddling and they knew to put their best foot forward."

Mr. Edmondson Clark added that it was an "amazing result."" He said, "Any time there is fierce competition like this, it will pay off handsomely for the seller.

Property records show the seller purchased the property in December 2014 for $912,000 dollars. That means they made a resale profit of $788,000, or about $130,000 for each full year they owned the home.

Nicholas Economos of Ray White-Rockdale, the selling agent, said the sellers were "very pleased" with the outcome. He said the home was popular before the auction, with 160 groups conducting inspections, 55 of which attended the first inspection.

"The location is great," Mr. Economos said, "and the exterior of the home is very nice." Buyers can move right in. People like the convenience. There aren't many existing homes in Arncliffe right now. And with the rising cost of building materials, no one wants to renovate."

Mr. Edmondson Clark said the few homeowners who are listing their homes are getting a return." Those sellers who didn't wait until spring are getting good results because buyer activity is still very active," he said.

In the western part of the inner city, a dilapidated rowhouse in Newtown in need of major repairs sold for just under $1.52 million, well above initial expectations of $1.2 million.

The two-bedroom, single-story terrace on Edgeware Rd attracted 10 bidders and ultimately went under the hammer for $200,000 above the seller's reserve price, which BresicWhitney's home-selling agent, Frederico Fraga-Matos, said was the seller's "dream price." He noted that the location and entry-level price pushed up the competition.

On the North Shore, a West Pymble home built a decade ago was re-sold at auction for A$4.33 million, with competition from six registered bidders resulting in a final bid of A$380,000 over the seller's reserve.

Records show the property on Warrabri Pl last sold for A$712,500 in 2009, when the original house was knocked down and replaced with a six-bedroom, three-bathroom home.

"We didn't expect it to go so well," said Jessica Cao, an agent with Ray White Upper North Shore.