WASHINGTON — Talk about your Black Friday sales.

Online entrepreneurs are hoping the spectacular fall of Gen. David Petraeus will bring sky-high prices as they hawk all manner of Petraeus-themed memorabilia on eBay this holiday season.

Since the scandal broke, buyers have been snapping up — and bidding up — autographed baseballs, military “challenge” coins, and signed photos of the former CIA chief, who quit this month after admitting to an affair with his biographer Paula Broadwell.

One seller was offering an “exceptionally rare” item: a “custom coffee mug hand-signed” by Petraeus when he was commanding general of forces in Iraq, for $850.

“He has now resigned due to an extramarital affair. Genuine Petraeus items are surely going to become much harder to find, and an item such as this is a one-time event,” the seller wrote, although no one made a $400 starting bid by yesterday.

The bids ran as high as $249 this week for a “Rawlings Official Major League baseball signed by Four Star General David Petraeus” obtained at a political event in Washington.

An embossed 2009 invitation to a dinner honoring Petraeus when he was head of Central Command was going for $24.50. Cream-of-asparagus soup and herb grilled chicken breast were on the menu.

Several sellers are trying to cash in on “challenge coins” that members of the military are known to carry and sometimes use to instigate drinking bets. Petraeus often had his staff pass coins with his insignia to people he met.

The asking price this week for one challenge coin from when Petraeus was at CentCom was $149. Earlier in the week, a Patraeus CIA coin sold for $182.50, and one from Baghdad sold for $152.50. The highest active bid last night was up to $142.50,

And mementos from Petraeus’ brief — and now unimaginable — flirtation with a presidential run this year also showed up.

A T-shirt emblazoned with a photo of Petreaus, with the slogan, “General For President” was fetching $12.95. And a “General Petraeus 2012” bumper magnet had a $6.99 bid.

Another seller wanted $34.95 for a “RARE and AMAZING 8×10 glossy photograph of the Beautiful Biographer of the Great General Petraeus!” But the offer wasn’t attracting any bids.

A “David Petraeus Paula Broadwell Wall Art Print 14 x 11” — basically a grip-and-grin photo of the two — was going for $19.95. The best deal of all might be the $4.95 one seller is seeking for a copy of The Post’s front-page Petraeus story headlined “Brass Balls.” The story details The Post’s exclusive reporting on efforts by Petraeus and Gen. John Allen to intervene in a child-custody case involving Natalie Khawam, military socialite Jill Kelley’s twin sister.

“NY POST CIA SEX SCANDAL David Petraeus,” said the advertisement, not quite up to the famed headline-writing talents of The Post’s copy desk.