Zilch. By the time we could do this and have it be economical, we would have had to have expanded to a point where the demand for minerals would be so high that this wouldn’t ‘crash’ their prices, just bring them down from the stratosphere. It’s not the supply of them in the solar system, it’s doing the work and extracting enough to justify the cost.
This is not a thing that will be economical for a long time.
Mining the moon is a bit more realistic because you’re talking about one destination where you have a massive front loaded cost, but then can stay there basically forever and repeat at much lower sustainment costs.
But even that, until you get fusion going (which is why it might become worthwhile) the demand wouldn’t justify the cost. And I personally think commercially viable fusion is MINIMUM a half century away. I’m a hugely pro-fusion guy, but I’m routinely annoyed by PR people overstating how close we are.
So don’t hold your breath even on mining the moon, IMHO.