Years ago I did some back-of-the-envelope commodities analysis on this. (Of course, the firm I worked for didn't represent it as such.)
It's worth more than "very little," though obviously not quadrillions of dollars. In the long run, the dominating component of unit costs are refining, not transport. The latter is amortized over a large mass; the former limits the rate at which commodity hits the market.
In the short term, measured in tonnes, it would be transport. Scaling such that the short term, in tonnes, is a short amount of time, in present dollars, defines the venture's economies of scale and thus minimum viable configuration.
They really aren't capable of capture. It hasn't been done yet, even for much smaller space rocks. This mission will "observe" i.e. fly by or orbit the rock.
That's all we're capable of now, so the valuation is quite moot and selling the mission on that basis is close to deceptive.
Talk about crashing markets.