20-year-old Marvin Coleman is facing charges of felony murder, robbery and other offenses.
Investigators say he killed 21-year-old Maribely Lopez, of Lindenwold, after meeting her to buy the phone in Willingboro Township.
Authorities allege Coleman made arrangements on March 6 through the marketplace app OfferUp to buy a used cell phone from Lopez.
They met in front of a vacant house in the first block of Medley Lane, which authorities say is a short walk through a field from Coleman's home.
They say instead of buying the phone he fired a bullet through her open car window, killing her. The phone was found by police inside the car.
Coleman was taken into custody during a traffic stop near his home on Wednesday.
The motive for the shooting remains under investigation.