First off, cars aren't investments, you will never get out what you put in. They need to be treated as tools, basically something to take care of a problem (get from A-to-B, pick up chicks, impress clients, etc.).
What exactly are you looking for, something that gets you from A-to-B? If so what's wrong with your current truck? It runs right? With a truck like that I wouldn't be that concerned about the rust or if the paint doesn't match, just that it gets me from A-to-B. I also wouldn't be putting any money into it unless it's to get a dead truck running again.
If you want something a little newer and more dependable you're going to have to spend $2,000-5,000.
My advice would be to keep it until you're out of school and have a full time job. While not putting a penny more into it that you don't haven't to, instead save that money.