Most of the tenants at the station under the Port Authority Bus Terminal were paying less than $200 a square foot annually, according to public data, with more than half shelling out less than $100 a square foot a year.

Rents are usually lower for subway stores than for their street-level counterparts because the stores are often beyond the turnstiles, so customers have to pay subway fare just to drop in. But the rents at the Port Authority Bus Terminal station shops are still well below market rate, brokers say.

Indeed, landlords ask more than $350 a square foot for aboveground storefronts in the immediate area. And in bustling Times Square, a block to the east, rents are far steeper, about $1,900 a square foot, brokers say.

The transit authority could use the extra money that renting out the spaces would bring in. It is seeking to invest $40 billion in repairs and improvements in the next decade, including upgrades to subway tracks and signals to make trains more punctual. Approved bond financing worth $25 billion, backed by new congestion-pricing tolls, and sales and real estate taxes are likely to help alleviate the financial burden.

But the authority, seeking to create new revenue sources, seems willing to embrace smaller-bore efforts, too. Vending machines selling toothpaste, deodorant, ear plugs and even colorful salads in jars have been popping up in stations. And the authority has been selling discarded train parts like seats, doors and maps. In August, a straphangers’ handle was available on its website for $25.

The redevelopment of the retail spaces may not create a windfall overnight, said Janno Lieber , the M.T.A.’s chief development officer. He joined the authority in 2017 to oversee infrastructure projects after playing a major role in the reconstruction of the World Trade Center for Silverstein Properties. But the new options will be appreciated, he said.

“We owe it to New Yorkers to create a dynamic subway environment,” Mr. Lieber said. “This is the right time for lots of reasons.”