I've spent the past 4 months obsessively browsing craigslist. This summer I moved out of an apartment (non rent-controlled) because my rent was increased from $2850 to $4,150. http://sfbay.craigslist.org/search/apa/sfc?query=&srchTy... is a search of 2br apartments in the city of san francisco, all neighborhoods. It returns 253 listings. Raising that to 3000 -> 4000 gives you 265 listings.
If I exclude the neighborhoods where I wouldn't live due to distance, safety, or a dislike of feeling like I'm in the burbs (bayview, excelsior, ingleside, north beach (fuck tourists), portola, richmond/seacliff, sunset, tenderloin) treasure island) then those searches (http://sfbay.craigslist.org/search/apa/sfc?query=&srchTy...) drop down to 106 and 184 apartments, respectively.
The competition for apartments is fierce right now due to a combination lack of credit keeping people leasing rather than owning, and the current tech bubble having imported 10s of thousands of new dot-commies happy to spend 50% of their salaries on housing, because they're young and stupid.
If you make under $150k, are fiscally conservative and don't want to live with roommates, then you're priced out of San Francisco.