The farm at the College of the Ozarks. College of Ozarks Facebook College of the Ozarks, a Christian liberal-arts college located in Missouri, has a $427 million endowment.

But unlike other private liberal arts colleges with large endowments, C of O, as it's often called, has accumulated its endowment all while offering four-year degrees to students tuition-free.

US News & World Report calls C of O a selective school; it accepts just 8.3% of applicants and has small class sizes with a 15:1 student teacher ratio. A total of 1,433 students attend the school.

While the school's policies state that 90% of the class must show financial need to be accepted, C of O spends about $18,100 per student every year, where a typical top 20 school spends in the $40,000-to-$80,000 range.

The college keeps costs down by employing students around campus. C of O students must work 15 hours a week as teaching assistants, grounds keepers, and farm workers. That work covers the full cost of tuition for students, who can choose to work additional hours to pay off the cost of their room and board. Students cannot earn additional wages from their campus jobs.

On the schools' farm, for example, students cultivate produce and raise farm animals to sustain their cafeteria. When there's a surplus, the students sell items at a farmers market to the surrounding community.

Students must maintain their campus jobs in addition to staying on top of their school work to remain enrolled at the college.

College of the Ozarks Facebook Dubbed "Work Hard U," C of O seems to have sense of pride in its somewhat gritty style of subsisting.

"If I were an employer, I'd take our graduates over those at most any other schools,"Jerry C. Davis, C of O's president, told the Wall Street Journal in 2014. "The kids at these East Coast colleges strike me as being a little spoiled," he continued.

Undoubtedly, C of O must work hard to maintain its endowment as well as its tuition-free model. It's one of only seven tuition-free work colleges in the US. Berea College, another work-based institution, also spends its money wisely. The liberal arts college located in Kentucky has a $1 billion endowment.

Student loan debt constitutes the second-largest source of consumer debt in America, and total debt has hit an all-time high of $1.2 trillion. Many, like outspoken entrepreneur and billionaire Mark Cuban, warn of a student loan bubble — and say it's going to pop.