ON MONDAY AFTERNOON, customers at Mondo Kim’s on St. Mark’s Place in the East Village browsed through finds like a Tomcats vinyl album recorded in Madrid in 1966; and Russ Meyer’s Faster, Pussycat! Kill! … Kill!, a self-described “ode to violence in women” that’s “filmed in glorious black and blue.”

On the third floor, video store manager Ricky Sutton presided over a collection organized by genres and the director’s place of origin. The employee picks included one of Mr. Sutton’s current favorites, Kamikaze Girls. The Three Burials of Melquiades Estrada played on a TV affixed to the ceiling.

“Every customer has been really sad about the possibility of this disappearing,” Mr. Sutton said.

Indeed, drastically falling revenues have forced Mondo Kim’s owner to put the building at 6 St. Mark’s Place up for sale.

Perhaps more important than the grimy, rundown, five-story building is that which it contains. There’s Kim’s beloved first-floor music shop and second-floor floor DVD shop will relocate to 124 First Avenue, between Seventh and Eighth streets. The fate of the third-floor movie rental shop overseen by Mr. Sutton depends upon the appearance of some sort of gallant white-knight character.

“Kim’s Video is offering a collection of approximately 55,000 films to institutions, schools, business owners or individuals” reads a sobering sign on the third floor of Kim’s three-story space. “The condition to accept this collection requires 3,000 sq. ft. of space, [a] commitment to give access to Kim’s members (charging minimum membership fee) and maintaining the collection.”

Mr. Sutton said that many of his clients are directors, producers, screenwriters and film companies who use the collection as a sort of library.

“I just don’t know of another source that stocks what Kim’s stocks,” said Ezra Sacks, the interim chair of New York University’s undergraduate film and TV department. “I’m always either sending students or running over to get some hard-to-find film.”

Kim’s founder and namesake, the reclusive Yongman Kim, got into the video business in 1987, when he devoted a corner of his Avenue A dry cleaning shop to rentals. He soon opened a store down the street, and ultimately had stores on Bleecker Street, in Morningside Heights and, of course, on St. Mark’s Place. Now, only the latter remains. It’s set to close by January, with its two replacements opening soon.

Mr. Kim has produced films in his native South Korea, and even directed a movie called 1/3, a mostly silent film about a Buddhist artist and a teenage prostitute that The New York Times called “self-enamored yet generally affecting.” (He did not respond to calls regarding the identity of the building’s $20 million buyer.)

One can only hope that his building’s new tenant will be as unusual as Mr. Kim and his predecessors.

Between 1834 and 1836, the building was the winter residence of James Fenimore Cooper. In 1912, The Times reported that the NYPD’s “Strong Arm” squad, after using axes in an unsuccessful attempt to batter down an ice chest door blocking entry to the second floor, arrested seven men for illegal gambling. Until the 1970s, the building housed a Turkish bath. In the 1980s, 6 St. Mark’s Place housed the St. Mark’s Bath, a gay bath house that the Health Department shuttered in 1985, in response to the growing AIDS epidemic. And in 2005, cops raided the store and charged five employees for trademark counterfeiting.

drubinstein@observer.com