Puzzled life, in my university almost all the labs have one or two or even more undergrads working as lab helpers. My lab has 4 or 5. Here almost every lab has helpers. If you haven't found any other on campus job, then I suggest you to check throught he website of the professors whether they are looking for any lab helpers or you can just go and talk to them. This is the easiest way to find an on campus job, as far as I know. A plus point in this job is that you can learn many things from the lab. If you don't like the job then once you get your SSN you can just quit it. I hope you understand what I said. Best of luck.