Prospinity cofounders Samvel Antonyan, Andrea Zanon, Aarya Agarwal, and Andrea De Berardinis.ProspinityProspinity allows college students to share in their success through income-share agreements.Just a year old, the startup already has hundreds of Ivy League students using its product.Prospinity raised $2 million to expand to new universities in a deal led by Slow Ventures.When they were freshmen at Yale, Aarya Agarwal and his roommate, Samvel Antonyan, struck a handshake deal.If either of them ever started a company that went supernova, they would sign away 10% of their income to the other."We shook hands, and at the moment, it was a bit of a joke," Agarwal said.