Trade Me's latest challenger is from Hawke's Bay businessmen Alan Slater and Wade Burrell.
SoldOne came about after a chance meeting of two Englishmen in Napier.
"Wade bought a table and chairs off me about four years ago from my shop in Tennyson St," Mr Slater said.
"Unfortunately it was about the time when the world fell over and I closed my doors and said, enough."
They put their heads together and decided to build an online community ahead of building profits, he said.
"We are not an international corporation with millions of dollars in our war chest, nor do we have hundreds of thousands of shareholders that need to see returns on their investments."
"Trade Me is a monopoly and last year they announced $111 million turnover, $56 million profit and then they put their fees up two weeks later. It all transpires now why it's come through - Fairfax jumped out and sold it and [took] the money offshore.
"In a period that has seen job losses, declining house prices, and increasing costs in all other aspects of life from fuel to consumables, we aim to break the trend.
"By offering realistic fees and rates we believe sellers are still able to make their profit margins at a rate that is competitive."
The site, www.soldone.co.nz has just gone live. It is having a "soft launch" in Hawke's Bay, ahead of their national campaign.
"We just want to test the server loads to start with. It shouldn't be a problem, but you never know."
While SoldOne's fees are a fraction of Trade Me's, for non-profits it is free.
"We want to build a community - and we want to give something back.
"All New Zealand-registered charities have the right to list and sell any item for free as part of any charitable event or fund raiser," Mr Slater said.
"All registered New Zealand schools, whether they are a day care centre, preschool, intermediate, senior, higher education, special needs or university, have the right to list and sell any item for free as part of any charitable event or fund raiser to replace old items that are being replaced with new - or just no longer required.
"Up and down the country sports and youth groups are constantly fundraising for new team strips, equipment, better facilities, field trips etc. All registered sports and youth groups have the right to list and sell any item for free as part of any charitable event or fund raiser."
Businesses are being offered free classified advertising - intended as a one-stop-shop online directory.
Ten per cent of profits are pledged to community groups nominated by the site's member forums.
Security is foremost in the SoldOne's creators' minds after the failure of Wheedle last year, which also took on Trade Me.
"There are several layers of security at the back end - the only way you could hack it is if you had the password," Mr Slater said.
Wheedle, bankrolled by Mainfreight co-founder Neil Graham, closed because of software-security problems.