money could simply be required to purchase jet fuel, climbing tools/ropes (and their respective bricks), air vent bricks, and things you need to dig deeper/not get stuck.
the ore picks themselves would simply improve your digging speed. money would be traded for these tools since even with them, you'll still need cash to dig deep.
edit: i think its time for you to summarize the current gamemode setup in your eyes, vis, so we can offer suggestions on the complexity and such.