Buying a “get out of jail free” card is just a mouse click away — and city officials are horrified.

Police union cards that cops hand out to friends and family free of charge are selling on eBay for as much as $100 a pop, even though the resale of the coveted plastic is strictly prohibited by the unions.

The cards are often used to get out of minor jams like speeding tickets or parking violations — flashing one with your driver’s license is a way of suggesting you’re a member of law enforcement or at least related to someone who is.

“It’s a way for a police officer to vouch for another person,” said City Councilman Peter Vallone Jr. “That type of recommendation shouldn’t be available to the highest bidder.”

But as a Post reporter discovered, purchasing police union cards — Patrolmen’s Benevolent Association, Detectives’ Endowment Association, the Lieutenants Benevolent Association and the Sergeants Benevolent Association are all listed — is as easy as logging on to eBay, charging it to a credit card or PayPal and receiving it in the mail.

One eBay seller, “anonymous1234567,” pointed out that some cards — like the 2013 LBA card he sold to The Post for $100 — work better than others.

“They do carry a bit more weight than a regular PBA card, as the union represents superior officers (bosses) and are harder to come by than the standard PBA cards,” he wrote in an e-mail.

A seller who goes by the eBay handle “joesstuff81” went the extra mile to hand-deliver a 2013 Gold Shield Association card for $20.

The card is distributed by the Gold Shield Association, which counts the PBA, DEA, LBA and SBA among its members.

The man, who lives in Brooklyn and gave his name as Lester, declined to say if the cards would confer any special benefits. He was also selling a 2013 Detectives’ Endowment Association card and a “2013 PBA/NYPD detective mini badge with numbers.”

“They make really nice collectibles,” he said. “People use them for the wrong reasons. [But] I don’t condemn that.”

Police union heads and elected officials are calling for a probe and an end to the practice.

“We need to do a full investigation,” said City Councilman Eric Ulrich (R-Queens), a member of the Public Safety Committee. “It’s an insult to the people who do work for the NYPD.”

Councilman Dan Halloran (R-Queens) fears that such cards could land in the hands of terrorists or criminals.

“Having the card in conjunction with a properly formatted wallet and a courtesy shield — that’s the problem,” said Halloran, who serves on the Public Safety Committee.

Councilman Dan Garodnick (D-Manhattan), another committee member, suggested that the cards be done away with altogether to avoid ethical breaches like the Bronx ticket-fixing scandal, which resulted in charges against 16 city cops.

“Our traffic laws should not be enforced with winks and nods,” Garodnick said. “I don’t know which is worse, the existence of a get-out-of-jail-free card or the fact that the cards are being hawked on the Internet.”

Eugene Loewy, an LBA spokesman, said that while the New York City police unions prohibit the resale of the cards, that’s difficult to enforce.

“It’s a form of impersonation, but it’s very difficult to take any prosecutorial action,” he said.

Vallone (D-Queens) said he would begin “exploring legal options” to outlaw the practice.