A CIA Special Operations group coin at Coin Squadron, which buys and sells the CIA-issued mementos known as challenge coins. (Kyle Grantham/for The Washington Post)

The coveted coins are cloaked in secrecy, just like the spy agency that produces them. So what are ­CIA-commissioned mementos — brass “challenge coins” most commonly associated with the military — doing up for sale on the Internet and by private dealers?

The unclassified coins represent something rare in agency culture: tangible and often darkly humorous acknowledgments of specific CIA stations abroad and operations divisions. Some coins contain symbols whose meanings are known only to insiders.

For such coins to disseminate widely — via eBay, no less — appears to fly in the face of the CIA’s tight-lipped and proudly cryptic culture. The agency, after all, doesn’t let ordinary people tour its museum or visit its Memorial Wall honoring slain officers. In some cases, employees can’t invite their own relatives to their own awards ­ceremonies.

Yet nearly 200 miles north of the CIA’s headquarters, a small business called Coin S quadron buys and sells pieces of Langley lore from the cramped basement of a converted church in Washington Crossing, Pa., right by the banks of the Delaware River.

This summer, Coin Squadron sold coins for the Iran operations division, the covert influence group within the agency’s Special Activities Division, and one that said, “Pipe Hitters Local 391” — 3 representing C; 9 for I; 1 for A. The coin’s back shows a smiling clown with an often-heard military slogan: “Be Polite, Be Professional, But Have a Plan to Kill Everyone You Meet.”

Joe Wallace holds a pair of CIA challenge coins that he is selling. He has gotten to know many current and former spies through his business. (Kyle Grantham/for The Washington Post)

“I got that one from a guy thinning his herd. He was retired. They made 50 of them. It was for some Special Operations group,” said Joe Wallace, Coin Squadron’s ­co-founder, whose shop has introduced him to current or retired members of the intelligence community. “Because of the business I’m now in, I get to talk to people I’d never get to talk to. They’re so proud of what they did. You feel it in them.”

One of Wallace’s favorites is still available: a coin issued by the Mexico City station showing eight menacing skulls.

“The number of skulls ­represents something,” Wallace said, “but I can only tell you off the record.”

Coin Squadron advertises its offerings heavily on its eBay page and through its Twitter account. Wallace says the spy currency comes directly from present or former employees or contractors. His freshest batch: a coin honoring the Tel Aviv station, another for the Pakistan ­operations group, and a third for a surveillance technology group that was staked out near Osama bin Laden’s compound in ­Abbottabad.

The going price can soar into the hundreds of dollars, ­sometimes exceeding $1,000. For each one.

Other rare ones reveal a sense of humor: One CIA coin offered shows a green Yoda from “Star Wars” aiming a sniper rifle and naming a specific location in Virginia. “May the Force of 7.62 Be With You,” the back reads, referring to a bullet size. Another from the Khost base in Afghanistan shows a bearded skull and says: “Admit Nothing, Deny Everything, Make Counter Accusations, Khowst OGA.” (OGA stands for “other government agency.”)

A CIA challenge coin specific to the agency’s U-2 spy plane group. The coins often contain insider jokes and dark humor. (Kyle Grantham/for The Washington Post)

In a statement to The ­Washington Post, the CIA didn’t express concern that its ­challenge coins are being traded in the public domain. A spokesman said the agency uses the coins as a “non-monetary award” to recognize exceptional ­employees. Agency employees in offices across the United States and world are free to design whatever coin they’d like, the spokesman said.

But eBay is also rife with fakes — coins that didn’t originate with agency people or that were copied by outsiders. In an interview, one former CIA security protective officer said he only buys and sells online with a few trusted sources.

“You also don’t want to sell it to a guy who’s going to start reproducing it and make 1,000 fakes off the one legit one,” the former protective officer said.

His personal collection’s best coin? A gold “Lethal Covert Action” coin featuring a skull and cross bones with “CIA” on the skull, crossed daggers underneath, and the letters “K” and “B” on each side.

“That stands for ‘Kill Bad Guys,’ ” he said. “It also has ‘D’ ‘O’ and ‘A’ in little red triangles next to the bones for ‘dead on ­arrival.’ ”

How’d he come to acquire it? The players in this world have a tendency to redact.

“I got it a couple years ago in a trade with someone still active,” he said. “It’s sort of comical and funny that this super secret agency has coins with all this symbolism floating out there.”

Many rare CIA coins are given to slain officers’ widows. The wife of an operative killed in Afghanistan said she was given a funny-looking coin by one of his colleagues after the funeral. It’s gold and has a green gecko on the front, standing up and leaning on a rifle.

Initially, the widow, who agreed to speak on the condition of anonymity, didn’t want to describe even the type of creature on the coin, fearing she’d reveal something too sensitive. But then she was told the coin was for sale on eBay and could be purchased for $250. The coin honors “Gecko Firebase” in Kandahar, and contains the Latin phrase, “Aut Concilio Aut Ense,” which means “Either by meeting or by the sword.”

“It would make me really sad if the coin came from someone posted there and then was trying to make a profit off a memory,” she said. “I will never do that.”

Former spies say they usually keep coins given to them under serious circumstances. A former member of the agency’s Special Activities Division said his favorite in his collection came from former CIA director George Tenet. He’d just debriefed with the spymaster after the death of Johnny “Mike” Spann, a paramilitary officer and the first American killed in Afghanistan after the Sept. 11, 2001, attacks.

“I was with Mike when he was killed,” said the former officer, who spoke only on the condition of anonymity. “Afterwards, Tenet gave me his personal coin — a simple bronze colored coin, with the company logo on the front, on the back, the director’s seal that says ‘Director of Central Intelligence.’ When he handed it to me, it was still in the manufacturer’s plastic wrapper. I can’t bring myself to open the bag.”

The one he’d really like? A coin nicknamed “Bush X” or “Maya.” But that coin is hard to find on the open market.

One Maya coin is kept in the collection in New York City at the 9/11 Memorial Museum. It was donated by “Maya,” the alias of the CIA operative whose tenacious hunt for bin Laden was dramatized in the 2012 movie “Zero Dark Thirty.” The coin features a red X on the front and the date of the bin Laden operation on the back — May 1, 2011. The 9/11 Memorial Museum said former president George W. Bush always drew a big red X through each al-Qaeda operative whenever they got killed or ­arrested.

Another “Maya” coin is on eBay.

But how did the eBay seller “rolyat11” acquire it in the first place? Denise Taylor, of Panama City, Fla., the person behind “rolyat11” declined an interview through her husband.

Its condition: “Unused, and in nice shape,” the eBay write-up says. It’ll only cost you $975.