The man took the card. Then the deliveryman shot him in the chest with a Taser.
The man managed to shut the door, and the deliveryman drove off in a silver minivan.
Three days later, John Felder, 76, of Miami, was in police custody, leaving authorities in Radnor Township investigating what appears to be a bizarre, botched kidnapping-for-ransom scheme.
"It's almost like a movie," said Detective Thomas Schreiber, one of the investigators.
Police said they had not yet found a criminal background for Felder, but they believed he had money troubles and, according to Police Superintendent William A. Colarulo, speaking at a news conference, had put together a "hit list" of possible targets and even had a location to take a victim.
Felder had also written a ransom note or notes requesting certain amounts of money, including payment in gold coins, police said.
In the driveway of the victim's home, police said, they found plastic ties and duct tape, both commonly used in abductions.
Later, in a rental car Felder was using, police found several cellphones, a stolen license plate, and night-vision equipment, Schreiber said.
Felder might have gotten away if, according to police, he had not gotten a parking ticket at an expired meter outside Cowan's Flower Shop in Wayne, where he bought the $100 floral arrangement - paid for in cash.
Felder's ties to the area are unclear. According to police investigators, he stayed in a local hotel in June. Schreiber said Felder once had a Pennsylvania driver's license, but not from this part of the state.
With the parking ticket information, police got a warrant for Felder's arrest. On Saturday, Felder tried to buy a firearm at a gun show in the Poconos. A required check turned up the warrant, and state police were alerted.
Shortly after being arrested, Felder was briefly hospitalized with chest pains, police said. He is being held at the Delaware County Prison with bail set at $175,000.
Arthur Thomas Donato, lawyer for the victim and his family, said they were grateful to police for their efforts.
"It's a very scary thing, and it's going to take some time to get over," Donato said, noting that the family had taken extra security measures at home.
An Internet property site estimates that the house is worth $1.3 million. Other houses on the street are listed for sale at several million dollars.
Contact Rita Giordano at 610-627-2649, firstname.lastname@example.org, or follow on Twitter @ritagiordano.
Inquirer staff writer Aubrey Whelan contributed to this article.