The seller met with the victim, 21, at 840 Grand Concourse about 12:45 p.m. on March 15, police said. When the two went inside, the seller's partner pulled a gun on the would-be buyer and demanded his cash, cops said.
When the victim tried to run, he was caught and assaulted, police said. The would-be thieves eventually fled empty-handed, cops said.
It did not appear that anyone was injured.
The attempted robbery came two days after the same suspects mugged a 17-year-old boy at gunpoint near Concourse Village East and East 156th Street about 8:40 p.m. before running off with his phone, cops said.
The first suspect is said to have a birth mark on the left side of his face near his eye and described as about 5-feet-9 and in his late teens.
The second suspect, who was the gunman in the Craigslist ruse, is also believed to be the same age, but slightly taller, and was last seen in a black hoodie with black sweatpants.
Anyone with information is asked to call Crime Stoppers at (800) 577-TIPS (8477).