One of the most potentially-interesting aspects of Elemental is (supposed to be) the process of rebuilding a shattered world. Unfortunately, my experience is that the item shop, as currently implemented, allows you to bypass all of that "rebuilding" nonsense. This is quite detrimental to both the narrative experience and the balance between different gameplay mechanics.
The problem is that everyone is measured in gold. Now, this works fine in the context of a massive, established civilization with existing logistics networks that provide enough raw materials from enough sources to allow market forces to set consistent prices. The world of Elemental isn't like that. The whole point is that civilization is non-existent. Regarding ordinary units, this system basically works: you need metal/crystal/mounts/elementium in order to equip them. You need to rebuild the logistical systems of a large, established civilization. You need to adapt your strategy according to the terrain, exploiting the resources that you have and compensating for those that you don't. For champions, however, you just plain don't have to give a damn. The only resource that matters to champions is cold hard cash. If you're focusing on champions, the only resources you need are gold and the materials to build basic structures (which is trivial). You can completely ignore the process of rebuilding - and it's usually far easier to acquire gold than it is to acquire elementium, crystal, or often even basic iron. This makes absolutely no sense in the context of Elemental's setting. Who the hell are you buying from, and why the hell are they willing to sell goods for cash alone - with the only restriction being that you've researched the items' required technology?
This dynamic also skews the balance between different gameplay options. I'll be frank: the caches and quest rewards containing special resources don't matter at all. I'll have outfitted my combat heroes with legendary equipment long before I've acquired any elementium (in fact, I never acquire elementium, because it's never worth spending the research up the quest tree to do so when I can buy elementium-based items straight from the shop). I'll have maxed out on magical trinkets without ever having built a crystal mine. And you'd better believe that I had iron-based weaponry before I even bothered to construct a mine on that iron resource within my borders. The item shop allows you to avoid managing any resources but gold.
I suggest a simple solution: change the price of all items in the item shop to their cost in unit construction. It really doesn't make sense that champions have an entirely different system for acquiring gear, and we'd have to actually care again about rebuilding civilization. We'd actually be happy to find sources of iron or crystal, and acquiring elementium from lategame quests would actually be meaningful. Legendary items would actually feel legendary, rather than being standard issue champion gear. The entire socio-economic system required to support a military elite would become palpable, and struggling for resource control (for things other than gold mines) would actually matter.
There's also the potential to return buying and selling for gold back to the system. Simply keep track of the type and quantity of items sold to the shop for money, and allow any player to purchase those items for gold alone. Same basic system, except that someone had to acquire and spend the resources to make the item in the first place. It'd also be both amusing and entirely logical if a strategy evolved around using the item shop to convert resources into gold (by crafting and selling equipment), allowing opportunists without the same resource access to acquire those items for gold. Perhaps limit the market of items a player sells to those neighbors with whom he has trading relations - suddenly there's another reason to establish trade relations with powerful, resource-rich factions.
I just find the champion game depressingly one-dimensional, given that the item shop's implementation currently allows the player to skip most of the game mechanics (and entire research trees) without thought. I believe that the best solution is to unify equipment costs between units and champions as a first step, then refine and develop the system from there.