What are some of the strategies folks use for finding subleases or temporary spaces? Since it's just 3 of us, we only need 150-250 sq ft, which is proving difficult to find.
E.g. In Alameda, I found a place for $1.80/sqft for a 70 sqft place. It was enough office space for just myself. Adding internet/utilities, still under $200. In San Leandro, found a 100sqft office space including internet/utilities for $250/month.
Also, another resource I found useful LiquidSpace. http://www.liquidspace.com
Edit: just saw your location requirements. My experience is mostly in the East Bay. Near BART, but a long ride to the peninsula.
* San Francisco Public Library has fast wifi, private meeting rooms, etc. I worked there for months after I got sick of giving Regus all my money.
* WorkShop Cafe (http://www.workshopcafe.com/) is awesome, and charges you 2 - 3 bucks an hour to work from their space.
* There are lots of free cafes, hotel lobbies, bookstores, parks with free-wifi, and other places to work.
If none of those work for you, check out WeWork, RocketSpace, NextSpace, Sandbox Suites, etc. There are so many co-working spaces available, that I'm sure you'll be able to find one. They typically have a waiting list for private offices, but there's enough turnover on the open-desk areas that you can normally squeeze in.
Don't expect it to be cheap, but they're usually not full. They (and others like them) have spaces areawide; you may find some discounts closer to Burlingame or San Mateo, as there's slightly less demand outside the twin orbits of San Francisco and Palo Alto.
If you're bootstrapping, you should defend why you're in San Francisco to begin with. Your runway is far shorter in SF; unless what you're working on will only work if you're there in person, or you're square dancing with funders each day, focusing on working almost anywhere else in the world would be smarter.