I'm going to make a controversial suggestion. If you believe you can maintain high grades, go to Berkeley and take on the $70k debt, especially if your ambition is to go to a T20 med school. And I am a little conflicted, but it's probably worth it at UCLA too. I would not take on the debt for USC as it is overrated imo and not worth the premium over Sacremento State.
Let me explain. I just completed this year's cycle and I can say categorically that Berkeley's students and alumni were everywhere on the T20 circuit. Berkeley's premeds are regarded very similarly at top med schools to the very best undergraduate schools' premeds. UCLA students grads/students were a little less prevalent. I met USC students rarely.
Don't let anyone tell you that the reputation of your undergraduate school doesn't matter when it comes to T20 med school admissions. It does. Not to say that schools that have lower rankings aren't represented. They are. Just not at the same high numbers. This is a hard cold fact of life. Perhaps unfair, but a fact nonetheless.
On taking on the debt. When it comes to medical school financial aid, the $70k is likely to be factored in, so it may not be purely added on. View your education as an investment. Berkeley in my opinion is worthy of that investment, and not simply because it will likely position you well for medical school, but it will provide a superior education.
Schools that are lower ranked are less represented because of the quantity and quality of students they tend to produce compared to T20 undergrads. That is the cold hard fact of life. Students from higher ranked schools are typically just better quality applicants and there are much, much more of them.
I go to unranked low-tier undergrad with about 95% acceptance rate. Excluding me, last cycle, EIGHT (8) people from my undergrad applied to med school. The highest MCAT of those 8 was 507. 2 got into med school, 1 of those schools is Ross.
UCLA supplied over 1,000. (
https://www.aamc.org/download/493728/data/factstablea2.pdf ). I can't give you hard facts on those 1000+ people, but I would make a strong bet their average stats are probably at least a standard deviation higher. Anecdotally, my SO's school supplies over 800 apps and I have yet to meet someone who applied with us last cycle from there with under a 510.
T20s generally offer much better advising and career preparation. However, anyone with google and who goes to a school with ample research, volunteering, adn EC opportunities could prepare themselves just as well.
Also FWIW, I'm going to T20 med school, at my interview my unranked, low-tier UG was brought up positively in my faculty interview.
Regardless of this, I do think that UG prestige matters, but more more in line with this chart than what most pre-meds think:
https://www.wellesley.edu/careereducation/sites/careereducation/files/mcatguide.pdf
