A onetime tented summer camp in Montauk is fast becoming a billion-dollar land tract.

The formerly lesser-known Montauk Shores, a collection of pre-fab dwellings — or as some might have it, trailers — in this once blue-collar community on Long Island’s East End has for years been known for its paradoxical nature. It’s the site of mobile homes, some of which not only belong to billionaires, but can also sell for millions of dollars.

And 2023 saw this oceanfront community reach new heights. Since 2022, the average sale price — already in the million-dollar range — jumped by more than double.

It all began early this year. In February, The Post reported that a trailer sold off-market there for a record-breaking $3.75 million. Not surprisingly, Montauk Shores homeowners seem smitten with Gold Rush fever. Another home popped up six months after with the asking price of $4.4 million. A month after that, in September, another home there listed, asking $3.6 million. By the end of November, another residence there hit the market for $3.95 million, with listings portal Out East noting it last traded hands in May 2022 for $975,000. That latter property is listed by Betsy Cronley of the Corcoran Group, who’s also repping a two-bedroom, one-bathroom listing elsewhere in Montauk Shores for $998,000.

These prices may not weigh as much as others when compared to the famously expensive Hamptons residential market, but they’re significant for this condominium of far more simple homes.

Montauk Shores, which took over the campsite on Deforest Road at Ditch Plains in 1976, became the first mobile home park condominium in New York State. But, with prices now in the multiple millions, this land parcel adds up to some of the most expensive real estate Long Island has seen — as much as $5,000 per square foot is mooted if the trend continues.

Montauk Shores’ sizzling scene has caveats and the main price driver is that old trope, “location, location, location” is key to fetching these high prices. Oceanfront in Montauk Shores carries a big premium; off-shore, not so much.

As for closed sales, the sharp increase in average price in 2023 is due to transactions for homes on Deforest, the prime street facing the ocean — but it’s pushing up prices across the board.

According to data from Corcoran, the average 2020 Montauk Shores closing price was $917,000, when six units sold. In 2021, another six units were sold and the price jumped to $1.18 million. In 2022, with the pandemic beginning to recede, only three homes found new owners, and the average price dipped slightly to $1.11 million.

However, three sales also closed in 2023 — and the average price has leapt to a jaw-dropping $2.5 million.

“Over the past few years Montauk Shores has seen some of the highest per-square-footage pricing in the Hamptons,” said James Keogh of Douglas Elliman’s Atlantic Team. “Over the last 10 years, it’s changed from having one of the lowest.”

Keogh delivered the February record-breaker, which sold off-market. That was an all-cash neighbor-to-neighbor deal.

“We represented the buyer who bought the record-setting one,” said Keogh. “The buyer lived next door and wanted an upgrade. We just sold his place for around $2 million.”

The record sale made waves even among locals, even among local real estate experts.

“That was a massive leap,” said John D’Agostino of Martha Greene Real Estate, LLC, of that transaction. “But it’s new and it’s oceanfront. It made people stand up and take notice. But all the units have been steadily increasing in value for a number of years.”

In September, D’Agostino listed unit 305, a 1,100-square-foot, three-bedroom, two-bathroom residence situated at least two rows back from the beach — though still very accessible, it’s not oceanside — for $3.95 million.

“My listing is a new unit, a whole new situation. It was brought in new,” he said of the pre-fab home.

“We’ve seen listings doubling through the Hamptons in general. The lack of inventory is one thing,” added D’Agostino. “There’s not enough sellers, because they can easily rent their properties. And there are plenty of buyers.”

Montauk Shores listings may use the condominium address of 100 Deforest Road, which is the oceanside road. But many homes actually sit farther back, away from the coveted ocean views. It’s still possible to find a Montauk Shores listing under $1 million; it might be one of the older trailers deeper into the condominium away from the sand. Pricing varies greatly — not just because of proximity to the Atlantic, or whether it’s a newer unit or one of the older trailer types.

“There are owner sites and there are leased sites,” D’Agostino said. “The maintenance for an owner is only $150 per month. But for leased sites it’s a couple of thousand per month. And you can’t rent those out. There’s a big discrepancy.”

“Both have pros and cons: It all depends on what you are going to use it for.”

Most want a Montauk Shores home for the ocean. Especially for the surf. Nothing to sniff at, Ditch Plains happens to have what many regard as the best surfing in the Northeast.

One thing that might temper pricing is that the condominium doesn’t qualify for financing.

“Only all cash sales are allowed,” added D’Agostino. “The buyer pool is somewhat limited by that. First you have to want it, and it’s not for everyone. Then, you have to have the cash in hand.”

But there seems to be no shortage of that. Surfing CEOs are flocking to Montauk Shores, and none are short on income.

“It’s young money, young CEOs,” said Keogh of the new residents. “There’s an obvious attraction for younger people with money who want two things: the outdoor activity and the nightlife.”

Thank you, East End party spot Surf Lodge, for the latter. (“Exactly,” confirmed Keogh.)

“Ditch Plains is the main draw,” he continued. “There are particular niches in the Hamptons, this is the surfer niche. People from Brooklyn, Manhattan and even overseas want to buy a front-row home to that surf.

Though D’Agostino’s listing has remained listed since September, the sellers are unlikely to drop the price, he said, and will wait for the spring surge.

“It’s typically light at this time of year. The market slows. Montauk starts to get cold. They will probably wait to see what spring opportunities offer,” said D’Agostino.

What’s to come in 2024?

“A lot of the prices we’re seeing in Montauk Shores are ambitious. But we did get an impressive $2 million for a trailer,” said Keogh. “So you never know.”