Property Brokers Whanganui branch manager Philip Kubiak said an Aucklander had paid $40,000 to $50,000 more than the accepted value for a central city house recently.
"What we had is an out-of-towner willing to pay significantly more money for the property than the locals were looking at."
That was becoming more common as Aucklanders looked to get more "bang for their buck" in the provinces.
Mr Kubiak said some of the area's most expensive homes had sold in St John's Hill, College Estate and Flemington Rd.
A lot of the cheaper sales were mortgagee sales, which could skew the figures, said Mr Kubiak.
Tim Hocquard, principal of Ray White Real Estate in Whanganui, agreed there had been some "rather ridiculous" sales at the lower end of the market. Some were mortgagee sales and others were Housing New Zealand homes, he said.
Mr Hocquard said the Housing New Zealand homes were underpriced.
"They shouldn't be given away, they should be revalued and resold at the same price as the house next door."
Mr Hocquard said any house over $400,000 was expensive by Whanganui standards.
He said the Dickens Lane property from the CoreLogic data was a semi-rural property. He believed the most expensive urban residential property last year sold for $580,000.
Mr Hocquard said just a handful of properties sold in that higher price range last year. However, sales of higher-end properties were exceeding everyone's expectations this year.
In 2014, the three most expensive house in Whanganui were in Otamatea, according to CoreLogic.
The most expensive was on Eaton Crescent and sold for $800,000.
The cheapest house in Whanganui in 2014 sold for $35,000 on Seafront Rd in Castlecliff.
Nationally, the three most expensive houses sold in 2015 were in Auckland. The most expensive was a house on Remuera's Victoria Ave, which sold for $13.99m.
The three cheapest houses sold were in Southland and the Bay of Plenty.
The cheapest house sold for $12,000 on Birchwood Rd in Ohai, Southland.
In 2014, the three most expensive houses nationwide were in Remuera and Parnell. The three cheapest sold were in Kawerau.
-The CoreLogic data refers only to market-level confirmed residential sales. Some big sales may not be included on this year's list if they are yet to settle.