The Lee’s building, at 220 West 57th Street, was originally a clubhouse for the American Society of Civil Engineers, whose members no doubt appreciated its delicate facade as they filed in and filled its 400-seat auditorium — until the building became a Schrafft’s restaurant. Lee’s, which had been across the street in a 500-square-foot storefront, leased the ground floor in the 1970s.

The owners of Lee’s bought the entire building in the 1990s and spent $8 million on renovations in 2001 and 2002 that increased the retail space to 40,000 square feet from 7,500 square feet. The extra room was on three largely unused floors upstairs. New escalators were brought in (through a hole in the roof) and installed at night. That let the store stay open by day.

In 2013 — five years after the death of Gilbert Steinberg, who had owned Lee’s since the early 1950s, and six years after the death of his wife, Ruth, who was known as Ricki and also had a hand in the store — the two children who had taken over signed a contract to sell the building for $65 million.

That deal crumbled, and in 2014, Thor Equities, a longtime commercial landlord, and General Growth Properties struck a new deal with the Steinberg children. The Real Deal website reported that the price was $85 million and that the closing was expected to take place next month. Lee’s, which has no plans to reopen in some other location, will continue its final sale until then, although many of its shelves and display cases are already empty. (David Steinberg, the chief executive of Lee’s, did not return a call seeking comment.)

So artists will have to look elsewhere for supplies. The Art Students League of New York, across the street, has its own store. “Anyone who’s mourning the loss of Lee’s can come across the street and pick up what they need,” Ken Park, a spokesman for the school, said.

But longtime customers like Ms. Simon, the photographer, will be left without the help that they counted on from Lee’s employees like Hector Alburez. “I have these silver gelatin prints and if one corner is dog-eared, the whole deal is off,” she said, adding that Mr. Alburez for years has packed them so that they were never damaged in shipping.

“He never talks about Brad Pitt and Angelina Jolie, even though I would see them in a magazine at Lee’s Art Supply,” she said. “I would say something to Hector, and he would never talk about it. And he’s somebody I’ve known for 38 years. I don’t want to overemphasize that particular star couple, but they’re there all the time. And Tony Bennett would be there all the time.”

Other customers, though, said the demise of Lee’s seemed almost inevitable.

“What in New York isn’t different from what it used to be?” Marty Merkley asked, checking discounted merchandise on Friday. “What was quaint is chichi and what was chichi is astronomically expensive. But that’s progress, whether we like it or not. Gentrification on any level is the lifeblood of any city.”