There was an article last week in the NYT about garages and what they add to the value of a property in Manhattan. Its in the millions. Chances are, if you pay a million extra for a garage, at the very least, you're parking a car there.
Admittedly, if you go far enough out in the suburbs, its not the case. But then you're in the suburbs, which has other challenges (transportation, etc).
All that aside, SOMA is where everything happens. If you can't afford to live there look incrementally further south until you find a place that you can live.
If you post that you're looking for roommates here I expect you will find some. Or http://sfbay.craigslist.org/sfc/roo/
1. Keeps you sane having other people about. 2. Means you're in a big place. Staying and working in a studio would be claustrophobic. 3. You will probably meet other people. 4. It's loads cheaper...
Course, if the flatmates aren't the right people then it would be hell on earth.
You should probably be upfront if you're planning on working from home - wouldn't suit everyone.