Instead of taking out loans, students can agree to hand over part of their future earnings in return for investment. To pay for college, Amy Wroblewski sold a piece of her future. Every month, for eight-and-a-half years, she must turn over a set percentage of her salary to investors. Today, about a year after graduation, Wroblewski makes $50,000 a year as a higher education recruiter in Winchester, Va. So the cut comes to $279 a month, less than her car payment. If the 23-year-old becomes a star in her field, she could pay twice as much.