I only have one summer class but I barely have free time as it is. I spent about 20 hours on Monday finishing up my homework in addition to two days during the week when I have class and can't actually work. Maybe in my freshman year I could have held a part-time job, but 300- and 400-level courses are far more time consuming. As for the other days, I guess I have those free more or less, but family matters and research takes up a fair amount of time. I'm a computer science major, so a lot of the stuff I learn is from other people or online in my free time. Pretty much everything I know about network security I learned by myself. I'm not sure I'd want to sacrifice that time doing something unless I'm going to learn in the process, so if I did try and get a job, it would have to be doing something computer-related.
The past two years my scholarships covered my expenses, but I'm probably going to be taking out some loans in order to finish.