It is good that you have a narrow focus. What specific problem do university students have that is solved by your product? Also, have you thought about how you want to iterate with a small group of users?
The problem is that often, a lot of University students are extremely unaware of how much they spend. I would argue more so than people that are more experienced handling their expenses. The amount of my friends that have said to me 'Man, I have no idea where my money goes, I don't but anything, but it just goes!' is crazy. If I can empower Uni students to make better financial decisions through a better understanding of their expenses.
Changing behavior is difficult. That's the reason services like mint rely on bank/credit card transactions to get the data. You may want to quickly start testing with a few university students before investing more development time.