The New York Post has uncovered a startling consequence of New York City’s ban on cellphones in schools: It's sucking $4.2 million a year from kids' pockets into the coffers of enterprising local businesses.

Mobile storage trucks and bodegas located near schools where the rule is enforced are charging $1 per day to store devices for students who can't take their phones to class, according to the report. And the fees are adding up, especially for low-income students.

"I cut back on food for the sake of my phone," said Emily Luna, a 17-year old student at a high school in Brooklyn, in an interview with the Post. "I try to cut down on whatever I buy so I have enough to store my phone."

The city’s controversial ban on gadgets in schools has incited strong opposition from parents and students since schools started cracking down on cellphones six years ago. Parents have argued that not allowing their children to have cellphones is a safety issue. Students have said that phones can be used as an educational tool and assist with cumbersome commutes. A recent robbery at one gadget storage truck has renewed such criticism.

But few local business owners are complaining about the crackdown. “It’s easy money. It’s all cash,” one school-safety source told the Post of the growing numbers of trucks and bodegas used by students to store phones. Such merchants rake in a combined $22,800 a day from students.

Vernon Alcoser, a Bronx businessman and former prison guard, is the man credited with creating the first gadget storage trucks. "A friend called me and said her daughter was storing her cellphone in grocery stores and bodegas in the area," Alcoser told Mashable. "[Students] were going away from the direction of the school in order to do that. I thought if we brought storage closer to the schools, it would be a favor to the kids."

Alcoser’s company, Pure Loyalty, now has seven trucks in seven boroughs. The trucks, like those of Pure Loyalty’s competitors, park near the 88 school buildings that use metal detectors to confiscate students' cellphones. Some store an average of 500 to 700 gadgets a day, according to Mashable.

There are 1,200 school buildings in New York City. But 90 percent of the city's schools don't use metal detectors, and with no real way of keeping phones out, the ban is largely ignored, The New York Times reported.

In 2006, the City Council voted to lift the cellphone ban, but Mayor Bloomberg vetoed the bill and subsequently defeated an override of his veto in court.

Students say schools that enforce the ban should offer more options. Bronx high schooler Jonathan Lauriano, 18, told the Post he'd spent $500 on cellphone storage at a truck near campus. “They should set up free lock boxes inside [the school] because we can’t all afford to pay a dollar a day," he said.

The Department of Education has largely opposed efforts to construct on-site storage facilities for students, arguing that the liability for schools storing thousands of phones and gadgets is too high. Pure Loyalty, for its part, has a $2 million insurance policy that covers just the phones, Mashable reported.