It’s the best rent deal in New York City: a SoHo one-bedroom that goes for the price of a porterhouse steak.

Thomas Lombardi, whose family moved to Manhattan from Italy in the 1940s, pays $55.01 a month for a one-bedroom at 5Spring St. — the same unit where he grew up and which he now shares with his much younger wife.

His monthly rent — which amounts to the price of a cup of coffee a day — has not increased a penny in at least two decades, according to state records.

“That’s the lowest rent I’ve ever heard of,” said Frank Ricci, director of government affairs at the Rent Stabilization Association, which represents 25,000 property owners.

When the landlord, Robert Cohen, bought the five-story, 15-unit brick rowhouse on the corner of Elizabeth Street last year for $3.9million, Lombardi, who is in his 70s, wasn’t the only rent-controlled tenant that came with the package.

Retired military meteorologist Tom Combs, 87, pays $71.23 a month for the 500-square-foot one-bedroom he has lived in since 1967.

The two pads in one of Manhattan’s most desirable neighborhoods would fetch $2,500 a month each on the open market, real-estate appraisers said.

The average rent for a one-bedroom in downtown Manhattan is $54.46 per square foot, according to appraiser Jonathan Miller.

But it’s unlikely that either apartment will go for market rate anytime soon.

“I hope to die here, but not soon,” said Combs, who is in good health and has no problem navigating the five-floor walk-up.

He says he has been blessed with good genes: His father lived to the ripe old age of 92.

In January, the landlord tried to evict Combs for “maintaining [the apartment] in an extremely poor and unhygienic condition,” according to court papers filed in city Housing Court.

The landlord called him a hoarder who created unsafe living conditions with boxes of books and tchotchkes blocking the doorway. But the judge ruled in Combs’ favor.

Combs, a published poet who was friends with William Carlos Williams, currently lives off an Air Force pension of $1,100 a month, according to court papers.

And he told The Post he earns extra money as a nude model for painting students, earning $18.50 an hour.

“They tell me I’m so good at it, I feel I have a duty to do it,” he said. “I have an interesting face.”

Because New York has legalized gay marriage, Combs said he is considering tying the knot with a 41-year-old former lover from Nepal who is seeking political asylum in the United States.

Under the city’s rent-control laws, the apartment would pass to Combs’ spouse after his death if the spouse had lived there from the beginning of the marriage.

Lombardi’s young wife, who would not reveal her name, would also inherit her husband’s $55 apartment.

Lombardi’s father was a famous photographer, his wife said, and the family owned a horse and buggy that supplied fruit and vegetables to the neighborhood — crowded today with models and hipsters.

Today he is retired, and she cares for him full-time.

About 1.8 percent of the city’s rental-housing stock is rent-controlled, according to the city’s 2011 housing-vacancy survey. The average price of the city’s 38,374 rent-controlled units is $800 a month.

To qualify for rent control, a tenant or family member must have been inhabiting the unit continuously since before July 1, 1971.

If they file paperwork with the state, landlords can raise the price of rent-controlled units by 7.5 percent a year until it reaches the “maximum base rent,” determined every two years by the state based on real-estate taxes and other building operating expenses.

Another 45.4 percent of the housing stock is rent-stabilized — where the rent can be raised by only 3.75 percent a year. The average rent of those apartments is $1,050 a month.

The average rent for a nonregulated apartment is $1,369 a month.

But Combs and Lombardi inhabit the cheapest apartments in the city — where the rents are frozen in time because the landlord at 5 Spring St. never filed the paperwork to increase the rent, according to the state Department of Homes and Community Renewal.

Landlord Cohen did not return calls or e-mails. But experts said his two rent-controlled tenants are burning through his bank account.

“If a landlord in Manhattan doesn’t get at least $1,000 a month [on a unit], he’s losing money,” Ricci said. “Since the city has no reluctance to raise taxes and water and sewer rates, it makes no sense to control the other side.”