The 3.0 GPA to get into the economics major is for the prerequisite requirements, not overall.
https://www.econ.berkeley.edu/undergrad/prospective/freshmen
If you have fulfilled MATH 1A and 1B with a 5 on calculus BC, then the remaining prerequisites are ECON 1 or 2, STAT 20, 21, (C8 and 88), or upper division, and ECON 100A, 100B, 101A, or 101B. If you like math, you may want to consider the 101-series with more math (prerequisite MATH 53).