The negotiated price was $17,500.

But the Elgin, Ill., family that 31-year-old Steven Marks, of Denton, Texas, was dealing with would only pay $8,600 for what he’d sold them, according to police — so Marks decided to reclaim what he’d sold, WFAA reports.

It wasn’t a car or a boat that Marks had exchanged, though. Marks had sold his daughter to the suburban Chicago family for sex in October, according to police records reviewed by WFAA. And after Marks drove to Illinois with his wife, Lila Miller, to pick up the girl in January, he planned to do it all again, police said.

This time, Marks was planning to “sell the child to another family in Florida,” affidavits obtained by CBS said.

Marks and Miller were arrested and are being held at the Rockwall County Jail, according to jail records. Both have been charged with selling or purchasing a child for sexual performance, and are being held on $1 million bond.

The child had been sold originally, police said, “so that the child would engage in sex acts and be involved in a common-law marriage to a male subject believed to be about three years older than the child,” WFAA reports.

The Texas Department of Family Protective Services has taken custody of the girl and five other children in the case, CBS reports. At least three of Marks’ seven children had previously been taken into Child Protective Services custody.

“They range in age from as young as 3 years of age to 14 years of age,” department spokeswoman Marissa Gonzales told the TV station.

Marks’ parents, Davy and Dorothy Marks, have been charged with interfering with child custody, jail records said. Police said that as authorities were interviewing Marks’ mother, she warned her son’s family that police would be on their way to the home where the teen girl was being held, CBS reports. Both parents told police they hadn’t seen the girl in four months, police said.

Then Miller and Marks left the home with the girl just before police arrived, their arrest warrants said, but the girl was able to escape to a nearby McDonald’s and call 911, CBS reports.

Marks told WFAA in an interview from jail that he didn’t sell his daughter for sex.

“A person that really does that needs to be put away for the rest of their life if they do that to their child,” Marks told the TV station. “I don’t think a father who loves his children, fights for custody for his children. I love them, I would die for them, I have no reason to sell my children.”

Marks also said that the teen girl had been in Child Protective Services custody, and ran away — possibly to Chicago — with her boyfriend, WBAP reports.