The first thing that you can sell in college are the notes you take in class. There are many ways to do this. Almost every major campus typically has a note-taking/note-selling service on campus. For example, the University of California, San Diego has A.S. Lecture Notes, which pays note takers and charges note buyers. However, there are also online services such as StudySoup, which allow students to sell their notes online. There are students who are making over $5,000 to $10,000 selling their notes.
Apply for new scholarships and grants. A lot of students think that they are only eligible for funding when they initially apply for admission. This is a mistake! There are often new scholarship opportunities for upperclassmen, though they aren't always widely advertised. You may also be able to apply for external scholarships or grants, which are offered from groups outside of your school.