Through their two sons' school they got to know the former Kauri House owner Peter Maidens, who was selling up to work in his wife's burgeoning Rock My Baby nanny agency which has gone global.
Mr de Groot said there was scope to grow the parallel Havelock North business they purchased with Kauri House, AA Hawke's Bay Removals.
Mrs de Groot worked part time for the Hastings District Council's rural fire service before she took the auction-house reins.
"I wasn't a regular but I loved coming to the auctions - my mum was the one that found Kauri House years ago - and then we just started coming when we could," she said.
They are enjoying the business and its many regulars. She likened the regular Thursday auction to a friendly church service.
"You ring the bell at 10 o'clock, everyone comes in, they take their seat, the auctioneer goes 'Blah blah blah' and bang, the gavel's down. We have had some amazing auctions."
They auction between 350 and 450 lots, with photos posted on Facebook on Tuesday night ahead of Wednesday viewing.
Auction buyers included many "entrepreneurs" who resold items on online auction site Trade Me.
"Trade Me is not the enemy - it is actually the assistant," he said.
The Antiques & Collectables Auction includes an original Peter McIntyre watercolour, a telescope, surveying equipment, tools, furniture and Belleek, Dresden and Royal Doulton china.
