Later this month, the long-awaited National Museum of African American History and Culture will open in Washington D.C.

The $570 million, 400,000-square-foot museum will contain an airplane flown by a Tuskegee airman, a lunch counter stool from the sit-ins in Greensboro, N.C., tiny shackles that fit a child, Chuck Berry’s red Cadillac and Harriet Tubman’s shawl.

It will not, however, contain any major artifacts from Martin Luther King Jr.

The story, first reported this week in the Washington Post, provided one more chance to shake your head at the King family, who, led by Dexter, his youngest son, has cheapened his father’s legacy by hanging price tags all over it.

The Post reported that King’s children called the museum with “an intriguing invitation,” that a curator traveled to Atlanta, reverently held the civil rights leader’s traveling Bible and then left without any arrangement.

You might remember that Bible. President Obama used it for his second inauguration (I believe free of charge) and it was also the focus of the latest King family feud. The King lads — Dexter and Martin III — squared off in court against sister Bernice. She didn’t want to sell the Bible and their father’s Nobel Prize medal, calling them sacred. Her brothers saw cash flow.

The case was settled last month. Hello, highest bidder.

Andrew Young, the ambassador and former Atlanta mayor who was with King when he was killed, seemed weary and a bit sad to be speaking about the King kids once again.

“This is a very complicated thing,” he told me. “There’s a lot of resentment on the part of a lot of black people who want to think Martin is everyone’s property.”

He said the King family was left with little when King was killed in 1968, and was kept afloat by an insurance policy taken out by the singer Harry Belafonte. (I may point out that Belafonte and the King children fought in court a few years ago when they tried to stop the singer from selling papers King gave him to raise money for charity. For charity!)

The King children have “had to monetize,” said Young. “You can’t expect them to be like their father.”

Dr. King started to focus his energies on economic justice toward the end of his life. His offspring have subverted that tradition, making lots of money for lawyers and themselves as they have zealously guarded their father’s words and image.

King as a speaker had a marvelous sense of timing. His kids do, too. The King estate (i.e., Dexter and Martin III, who seems to get pushed around by his little brother) filed suit on Aug. 28, 2013, to put sister Bernice on administrative leave from the King Center and to bounce Young, who is almost their uncle, from the board. That date was the 50th anniversary of the “I Have a Dream Speech,” which you can rent if you have your Visa ready.

True, the Kings have suffered untold tragedy and they own their father’s memory, or at least his copyrighted words, which Dr. King was wise enough to do, leaving them a legacy. And they have thrived, especially with Dexter, a capitalist at heart, at the helm. Years ago, he visited the Elvis Presley estate to see if the other King’s handlers could give him some tips.

And Dexter has had the King Midas touch, helping land a lucrative deal with Time Warner in the 1990s. A decade later, the estate sold some 7,000 pages of King’s papers for $32 million to an Atlanta group worried the collection might end up elsewhere. The private fund raising stalled during the recession and the city ponied up about a third of the cost. The papers are now at Morehouse and the city’s Civil Rights museum, the one next to Coke’s.

They say the African American museum in D.C. has been 100 years in the making. And civil rights icon C.T Vivian has been alive for most of that.

The 92-year-old is headed to Washington for the Sept. 24 opening, getting a personal invite from Obama, who in 2013 awarded him the Presidential Medal of Freedom.

He hadn’t heard the museum would have no major King artifacts.

“That hurts because I can’t even imagine that there’s anyone who wouldn’t want to be involved, especially at the top of the ladder,” he said when reached at his Atlanta home.

“I used to say, ‘This is our Royal Family. Why not make sure they have money?’ ” he paused, adding “but…”

And then he paused again, not wanting to say anything untoward about the Royal Family.

Taylor Branch, who authored a trilogy of books on King’s life, chuckled when I mentioned the museum couldn’t work out anything with the family.

“They wouldn’t be the first,” he said, adding the family went hot and cold with him decades ago as he researched King. But that was in the ’80s before the kids ran the show.

Branch has been on the museum’s historical advisory board and said King wouldn’t necessarily be the focus. “It’s about how African American history is intertwined with American history,” he said. “It’s not about one person.”

He said one section of the museum is called “Making a Way Out of No Way,” a reference to an old saying about overcoming obstacles.

“There’s a lot of ways to tell a story and artifacts aren’t the only way to do it,” he said. “You’ve got to make a way out of no way.”