Unfortunately you're going to have problems finding "cheap" storage anywhere near San Francisco.
If you're wanting a secure location, figure a minimum of $100 per month.
And that will outside the SF area.
Dan-Retired California Firefighter/EMT
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
4pt Equal-i-zer WDH and 1828lbs of payload capacity