The parents, 37-year-old Deanna Lynn Greer and 26-year-old John David Cain from Tennessee in the US, were arrested on Friday and have been charged with aggravated child abuse and aggravated child neglect or endangerment.
News.com.au reports via AP that local authorities were alerted when another couple saw the ad and contacted them.
The couple were arrested using an undercover investigator, who contacted them via Craigslist and agreed to meet with them and exchange the money for the baby.
When the exchange occurred, the couple was immediately taken into custody.
The baby is now reportedly in state custody, and the parents are being held on a $150,000 USD bond.
This article originally appeared on marie claire.