The country's largest house sales website showed Auckland's asking price hit a new all-time record of $732,240 last month.
Paul McKenzie, Realestate.co.nz marketing manager, said there had been a big jump from April's average asking price of $685,426.
Mr McKenzie said a lack of listings meant sellers knew they could achieve big prices because buyers had so little choice.
"The high asking prices in Auckland, in particular, suggest that home sellers are confident they will get their price. A factor in this may be the low overall supply of homes on the market. Auckland home sellers want more for their homes than ever before," he said.
Nationally, the number of homes newly listed for sale was the lowest on record for June of any year, his data showed.
The total of 8524 new listings is 20 per cent less than the month before, and 6.1 per cent less than June last year.
Only Canterbury, Wellington, Northland and Coromandel experienced an increase in listings from the same time last year, while four regions recorded their lowest number of monthly new listings on record: Bay of Plenty, Central North Island, Gisborne, and Central Lakes, Mr McKenzie said.
"The low number of new listings brought the overall number of homes on the New Zealand market down to just 38,693, one of the six lowest monthly totals we've seen," Mr McKenzie said.
"However, buyer interest is still very much in evidence. We get more than 45,000 potential home buyers visiting the realestate.co.nz website every day. These are all people specifically looking at properties for sale or rent."
Labour's housing spokesman, Phil Twyford, said the new asking price was "crazy" and further evidence of the Government's failure to quell the market and get more new houses built.
"LVR minimum deposits and interest rates heading north of 8 per cent have collapsed sales at the affordable end of the market," Mr Twyford said. "First-home buyers have been squeezed out, but the record-high prices suggest cashed-up speculators are having a field day. The Government has not built a single new house in the Special Housing Areas, and refuses to tax speculators. Until they do both, this crazy situation will continue.".
Mr Twyford said data from Auckland Council chief economist Geoff Cooper showed Auckland was on track to build only half the number of houses the council said the city needed to keep up with demand.
Housing Minister Nick Smith said 63 Special Housing Areas for 33,500 residences had been established under the Auckland Housing Accord. A fourth tranche of new areas would be announced next month.
Asking a lot
$732,240 Auckland average asking price in June
$685,426 average asking price in April