Dropping 50$/person on dinner & drinks in sf isn’t that much money when your rent is 50x+ that figure.
If you want a great literal hole in the wall, try Yamo in the Mission. Burmese food, grand total of 6 seats (all at the bar) in the restaurant, and the entire kitchen is right in front of you. $6 entrees.
While I haven't been up to SF proper for food and barhopping in a few years now, the Lark up in the financial district is much more of what I'd call a good cheap bar. I tend to bristle a bit at people dissing the SF food and drink scene, but I have to remind myself that with few exceptions my favorite places in the Bay Area aren't actually in SF itself. The metro area as a whole has virtually everything you can imagine at a very wide range of price points. I suspect one could make a case that the most interesting stuff happening is in the East Bay and South Bay, though.
Within a narrow window. The diversity and turnover of New York or London’s food offerings compared with the Bay Area’s is on par with the latter’s offerings in relation to Fresno’s. If anything, the Bay offers its uniqueness in the middle tier of immigrant fusion.