Look at MiraCosta Community College in Oceanside. It is just west of San Marcos. There are apartments in the area, and limited bus and sputtering E-W train possibilities maybe. You could transfer to CSU San Marcos. Housing North of the freeway, in Vista and up into the more rural parts may be passable, or you could commute from the San Luis Rey area along the 76. Going south or east may be more difficult to find reasonable rent.
Some students at UCLA will get a 1 BR and put two beds in the BR and 2 beds in the common room for cheap rent (4 in a 1 BR). There are spare rooms and granny flats around San Marcos and Vista and on into Oceanside.
CSU Channel Islands is in an affordable area around a Navy base and agricultural fields (Port Hueneme, Oxnard, Camarillo). It is in the place that is rumored to be the model for the song “Hotel California” and supposedly is the site of the Album cover photo; also the subject of Zappa’s “Camarillo Brillo”. Converted from an old mental hospital.
CSULA is possible, but may not be the most pleasant experience possible compared to the other schools. Some parts of Boyle Heights, if you choose the right block, may be a good place to rent, or just up the hill from Lincoln Park, towards the 110 freeway.
You really may find some luck in applying to a private school such as Cal Lutheran, Soka, or perhaps even Chapman. Check out available scholarship money. You may (or may not) be surprised. Have you thought about going through Questbridge.org for some guidance?