I thought the assumption is that tier two has nothing to offer tier one and is technologically much inferior due to tier one being AI driven. So if tier one needs something from tier two I don't think they need to even ask. Wrt market equilibrium. Indeed i think it will be at equilibrium with increasing cost of extraction so indeed they will not spend arbitrary amounts to extract. But this also means probably there will be no way way for tier two to extract any of the resources which tier one needs at all bc the marginal cost is determined by tier one