"I call it the 50-20 formula," says David Bach.
"It's time to stop wondering where all your money goes each month," Ramit Sethi says.
He says it was one of the greatest moments of his life.
"I didn't own my first car until, I think, one of my first car sponsorship deals."
Purdue University says it is the first four-year institution in the country to offer an income sharing agreement, or ISA. Under Purdue's Back a Boiler program, graduates make payments for 10 years after graduation.