Economy wise, materials are what will be expensive, not by type but by place where they are sold VS where they were harvested.
Tartaros materials will be cheaper on Tartaros, but expensive on Arboreus. And vice versa. Also gear customized with Tartaros materials will be expensive on Arboreus. And so on, you get the point.
Cheapest will be Arboreus materials, sold on Arboreus, because it will be world full of PvE players grinding in peace. RISK FREE. Tartaros materials, sold on tartaros will be more expensive than Arboreus materials sold on Arboreus.
Gear progression will be horizontal. You will need multiple gear pieces for different situations, and if you loose fore example your fire resistance gear and you are human or beast and you require Tartaros materials, and you wish to buy them in Syndesia or in Arboreus you will pay more expensive (or if you are buying directly FR gear on those 2 planets).
Economy focus will not be on crafting and selling, it will be on TRAVELING, because crafting isn't risky... you can craft in safety of your home. TRAVELLING is what is risky. In travelling you can lose everything.
So if you want to get rich, you will have to risk a lot travelling with goods through open PvP full loot world.
Do NOT be mistaken, there will be no riches in risk-free activities.
I just hope DS sticks to their word and does not make all materials available on all planets (not even in low quantities), because that would outright ruin the game completely.
part of materials needs to be unique to particular planets
there should not be alternate materials on own plaent, that can replace materials that exist only on another planet.
This means if you wish to craft a certain item, and it requires materials form other world, there should be no way possible to craft it with alternate materials. You should either pay for those materials more expensive to someone that risked bringing them to you, or you should go take a risk and travel yourself.
There should also be no alternate items that are craftable with materials from own world, and offer more or less same thing as that item that requires materials from another world.