The Far North is a particular problem, but the same issues are hurting property owners at all the seaside holiday centres - from the Northland coast, the Bay of Islands and Ruakaka down through the coastal belt north of Auckland and to the Coromandel and Bay of Plenty.
Real estate agents in coastal areas suggest today's holiday home prices are down between 15 to 30 per cent on the boom peaks, and heading towards the levels of 2002 or 2003. That's eight years of zero capital gain as the mortgage, rates, insurance and maintenance bills keep flowing on a property that may only be used a couple of months a year. Lying ahead, sooner or later, is a Labour-promoted capital gains tax.
Scores of properties have sold in stressed sales since 2006 and many other bach owners have lost a lot of money.
It's not a major problem for everyone. The family bach that Granddad built will stay to welcome another generation, and the well-capitalised will suffer any paper fall and still enjoy what the seaside offers.
For her part Ms Boyd is optimistic the family property will find a buyer.
"Ours is actually very good value because for something in the order of $200,000 somebody can have all the advantages that [are] really worth about $600,000."
She has only recently decided to sell the share in the beloved holiday home the family have had for 25 years and built up with extra rooms, decks and fruit trees in the garden.
She said she had already received several inquiries and was expecting a further pick-up through the summer - but was also prepared to negotiate on price and amenities. A question from a potential buyer had led her to offer two years' rent on boat storage as part of the package.
Three families own the bach together and each has access to it every third fortnight. The shared arrangement led Ms Boyd to market the property herself rather than going through a real estate agency.
The family are moving from Auckland to Mangawhai so have no need for the bach - but there are many sentiments tied up with the property.
Ms Boyd's son Tim Boyd-White said: "It's sad to be letting it go. It was always getting used - it was right by the beach and the estuary, and it's a beautiful place to go over winter as well. There's a potbelly fireplace outside with decks on either side."
Further south, in Martins Bay, Grant Chalmers has since April been looking to sell the bach originally bought by his late father.
"We got it when I was a teenager and I'm now 50 - but unfortunately my children haven't got the bug, and that makes it awkward because you're driving them up there and they're not happy. There's no internet. I've admitted defeat on that one."
There was some initial interest when the bach was posted on Trade Me, but after listing an asking price of $700,000 two months ago inquiries dried up. Mr Chalmers said he was in no hurry to sell.
"There's been a lot of people looking for a bach but not those who want to pay a lot of money. It's top dollar but we don't care how long it takes to sell. We're very relaxed about it."
The coastal mess has its genesis in the confident times of the mid-2000s when too many people used easy finance to accept the line that nothing would stop coastal values from rising forever. Tracts of land were opened up as the banks and finance companies backed developers. But the bubble burst, leaving a trail of misery.
Just one example: Doubtless Bay Villas at Coopers Beach in the Far North.
Off the plans in 2006, you could have bought one of the 25 elegant modern villas - each spread over 172sq m, with three bedrooms, stylish bathrooms, finest European appliances, granite benchtops and all the trimmings - for $750,000 to $820,000 (and annual rates bills of $4000-plus, along with body corporate fees of $5000 a year).
Only 10 of the properties had sold by the time the first villas were completed in 2007, and a year ago more than half remained unsold. Two were sold by mortgagee tender in the spring of 2010 - one for $381,000, the other for $330,000. Both were fully furnished and neither sales cheque would have covered replacement cost, let alone land value.
Now, a year or so on, three more are being offered in a receivership sale, with a starting price of $319,000.
Economist Dr Rodney Dickens, whose Strategic Risk Analysis company closely watches coastal trends, says the region is "drowned in over-supply".
His review of Real Estate Institute median data suggests section prices in the greater Mangonui area - from Taupo Bay to Karikari Peninsula - have fallen 42 per cent from the 2007 peak.
"The demand-supply balance in this market remains extremely challenging for would-be vendors ... and prices will continue to grind lower for some years," he says
He believes the slide has a way to go yet: "The cold hard fact is that prices are still too high relative to what the bulk of would-be holiday home owners can afford."
