Enh, it's really about personal comfort. If you can get through sprints and olympics without any chamois padding, then there's no reason to get tri shorts. If you are planning on doing halfs or fulls in the future, however, I believe that a pair of cheap tri shorts may be a good investment, even on a college budget.

You may want to get some chamois cream, as well--this will help out on your longer rides if you are running minimal to no padding.