This year’s auction was held in the Buffalo Niagara Convention Center, in a garishly lighted room redolent with the scent of the attendees’ breakfast choices and punctuated by the whir of the currency counters. Winning bidders paid 20 percent of a property’s price in cash or certified check. The balance is due in December, and they should receive the deeds in March — a schedule that had severe consequences last year, Mr. Wilson said. “The owner turned the power off in one of the houses we bought, but not the water, so the pipes froze and burst. There were mushrooms. It was horrible.”

This year, he and Ms. Radle were tentatively interested in a few properties, if they stayed below $25,000, which they didn’t. Prices seemed to be up by a third over last year, Mr. Wilson estimated. But mostly they were there to buy the vacant lot next to their cottage, which they hoped to make their home. Happily, the lot was unchallenged, and they won it quickly for $500.

It was time for a tour. On Massachusetts Avenue near Chenango Street, there were the meticulous properties of Push Buffalo, a community organization that creates affordable sustainable housing. Across the street were spiffy clapboard houses painted in bright pink and yellow, one sprouting an elaborate Victorian porch that had been salvaged from a house lost to arson in another neighborhood.

Joseph Galvin owns these and seven other properties. Mr. Galvin, who is 57, was one of the first to start rehabbing in this neighborhood. It was more than 25 years ago that he bought his first property, the yellow house on Massachusetts, which was then a boarded-up wreck owned by a bank, for $13,600. “At first it was necessity — I just wanted a place to live,” he said. “There were a lot of drugs and prostitutes and criminal elements. We’d call the police, and they’d arrest someone, and then there’d be someone else to take their place. What I decided to do was to buy these houses and renovate them and try and save a neighborhood that was in decline.”

He added: “I was a lone soldier for a long time, dodging bullets and drug dealers and baloney. Lo and behold, now I have nine properties. We missed the whole rust-belt revival that cities like Cleveland had. Now it’s our turn. Now the young kids like Jason and Bernice are just coming out of the woodwork.”

On Chenango, Mark Legeza’s front yard was still a riot of greenery, with Japanese wisteria climbing up the porch. Mr. Legeza, 29, is a health physicist for the Army Corps of Engineers. (He is overseeing the cleanup of radioactive materials from the Manhattan Project, not a job you hear about every day.) In 2009, he bought his house for $70,000. It was in good shape, though it had been neglected. But his block had its challenges, including two rowdy drug houses, he said, which he bought in 2011 for $30,000 and $25,000, using a home-equity loan for the first, and a high-interest loan for the second. The renovation, which cost about $36,000, he did himself.