My case won't be much of an help for an ordinary American student because I am an international student.
I went to a community college for an year, and applied for an econ major with a GPA of 3.2. That's pretty low to get into an econ major at UCSD. I think the reason why I got into UCSD econ major is because I had a pretty good personal essay. I emphasized that I didn't speak any english at all before I came to the states, but I managed to finish my GE requirements in one year at a community college, and I talked about how hard working I am.
I'm pretty sure that you can get into UCSD if you talk about your special talent (or why you think you would be a great UCSD student) in the essay even if you don't have a high GPA or SAT score.
you might hear some criticism about UCSD econ major, but UCSD is afterall a great school, and I'm sure you'll enjoy it once you are here.