You probably do NOT need to buy a new camera; what you already have will work.
If you do not have a camera, remember that many universities, including the University of Illinois, have cameras you can borrow, and some departments are willing to purchase equipment for its students. The Media Commons at the Undergraduate Library has several types of digital camera that can be borrowed through their Loanable Technology page.
If you wish to purchase a camera, and price is a consideration, used or refurbished cameras are much cheaper than new ones, and often they meet your needs perfectly. Be sure to check ratings and camera capabilities online before purchasing. If you can, test a camera in a store to see how it feels and what functions it has. This page has some information about different features you might look for.
Remember: you don't have to have all of the following features; some you might not use or even like. They are just things to keep in mind when using or buying a camera.
Remember: The digital camera you already have should work, but if you wish to purchase a new camera, there are several good brands to choose from. Some to consider are Canon, Fuji, Olympus, Nikon, and Kodak, but there are other equally good brands.
There have been good reports on the Fuji brand F10 through F31 series because it performs well in low-light conditions.