One warning: even if you get into Berkeley or off of the wait lists for UCSD or UCLA, you will have a very hard time getting into mechanical engineering. Possibly near-zero. Look into the process for transferring into the engineering college at each school and do some searching on College Confidential. CMU might be your best hope; beyond that, community college is a great deal and a great option, though transferring to UC mech eng programs will be competitive there as well, I believe.