Esmerelda Garza, 29, and her boyfriend owed money for drugs, police say.
And she was willing to sell anything, or anyone, to pay it off, according to the affidavit.
Troopers with Texas' Department of Public Safety arrested Garza and two others Friday as she attempted to complete the sale of her 7-year-old son to knock $2,500 off that debt, according to KIII-TV.
They executed a search warrant at a home near Corpus Christi on Friday. A woman in that home admitted to police that she bought the boy from Garza for that sum, according to the Corpus Christi Caller-Times.
"Wow. Just the type of stuff that you see in movies," Tony Guerrero, the boy's uncle, told KRIS-TV. "And it really happens. For it to be happening here in Corpus Christi is what's the scary thing."
Even worse for Tony and Sandra Guerrero, the boy's grandmother, it happened in their own family.
"We're saddened by the whole ordeal, but as soon as we get my grandson home, everything will be OK," Sandra told KRIS-TV. "We intend to take care of him the best that we know how."
The boy, and his two sisters, 2 and 3, have been in Child Protective Services custody since Friday. Police told KPRC the two young girls were also in the process of being sold.
Garza was still in Nueces County Jail on Thursday with bail set at $100,000. Selling a child is a third-degree felony in Texas.
DPS officials told KIII-TV that additional charges against the man and a woman arrested with Garza are expected.