The US emits about 11 gigatonnes of CO2 per year. At $150/ton, sequestering it all would cost 1.65 trillion dollars or about 8.25% of GDP.
That's about what we spend on social security and the military combined.
So, it's a lot. But it's possible to imagine doing it.
I kinda wish there was a company with a bunch of sequestration equipment out somewhere that people could just give money to in order to suck out more CO2 from the air. Why doesn't this exist yet?
China emits 11 gigatonnes. The US emits ~half that. So more like 800 billion or 4% of GDP. About what we spend on Medicare.
Of course, even if US emissions went to zero, it wouldn't be enough to stop global warming. So there's that.