Hi Camille,
Congrats about USC, regardless of your concern over the pricetag. I myself am going through a sort of crisis about how many loans I am going to graduate with, and crossing my fingers for the scholarships I applied to. Did you get any word from any of their scholarships? If you haven't, it very well could happen any time between now and the beginning of classes. I guess they have to see how many people are accepting their seats first, before they disburse the goodies.
I don't know much about Cal State MSWs, as I only applied to USC, but I do know that USC has a lot more seats to offer than any Cal State, so it is technically more competitive to get into a state school. I have also heard many good things about CSULB's MSW program. I work with a social worker that graduated from USC and she told me to really consider CSULB because I would be saving a tremendous amount of money and still have a very good education. I did consider, but I grew up around USC and its reputation, so naturally, it is the school for me. I might bite myself later when I start paying off loans, but I cannot regret something that I dreamed of doing.
I don't know if I answered anything for you, but I just wanted to say hi and a little bit of what I know. Have patience and time will go by faster =]
Good luck!