20 sqm (about 215 sq ft) is probably the size of a lot of studios in manhattan that you'd find for $1800/month or so if you were lucky. You'll obviously get a lot more in Brooklyn for the same price (mine is about 450 sq ft).
You just have to be creative about your use of space in the city. It doesn't end up being all that hard, you end up just pairing down.
My boyfriend and I live in a studio, large enough for the both of our "startup lifestyles", and we pay less than that in a safe neighborhood in Manhattan, close to a subway line that can take us practically anywhere in the city. This isn't a particularly rare gem, you just have to know where to look.
You just have to be creative about your use of space in the city. It doesn't end up being all that hard, you end up just pairing down.