So, recently I came upon the thought of making a sect that is known for working with Force-attuned crystals and other related artifacts, and in debating what different kinds of crystalline-based armors and robes they might wear, I had a startling realization: just how much would something like that really cost?
Economy is a funny but relatively straightforward thing. People look to buy low, sell high, and maximize their profits and returns in any way possible. How does this affect gems, crystals, or virtually any valuable and rare commodity? Well, I looked at diamonds. Diamonds are one of the most highly valued things on earth. They're valuable because they're nice to look at with physical properties that very few other materials on earth have, they're incredibly hard and are extremely useful in industrial applications, and they are also just generally very rare taking millions of years to form under only the perfect conditions and no way of perfectly synthesizing the process.
What if there was another planet of another system not too far off that is rich in both carbon and carbon-based life forms? What if their planet just naturally has an abundance of diamonds? Wouldn't diamonds be much less treasured there due to their commonality, and thus be worth much less to the inhabitants of this world than they are to our own? That's when the bigger question comes into play: How does this affect the galactic economy?
The short answer is that the galaxy is an incomprehensibly -HUGE- place, no matter how explored or traversible it becomes.
There are always going to be localized pockets of goods that are worth much less and come in much greater quantities than in other places. The further away one gets from the source, the less become available and the higher the cost becomes. There is no "galactic market" like Amazon where someone can just look up a particular kind of product online, find the cheapest retailer, and then order it from halfway across the known universe. Even with means of traveling faster than light or folding space (or any other means of feasible intersteller travel), shipments in freighters or barges could take days, weeks or even more, factoring in all the other systems and planets they must stop along the way for deliveries, pickups, rest, refueling, maintenance and everything else such a starship operation undergoes. There is also the factor of mortality; individuals who pilot these ships and offer these services do not live almost indefinitely just because the ability to move has become almost indefinite. Some may simply be unwilling to make the journey. These factors make getting such materials from any chosen sector of the galaxy extremely difficult if not impossible, and thus doing so would almost certainly cost much, much more than it normally would, defeating the purpose of the purchase from that source.
To put it simply, there is no "galactic standard" value for anything short of ancient artifacts and old museum pieces, or anything that exists in small, set quantities with no particular geographical bias on marketability. The galactic economy could be isometrically charted out much in the same way as gravity could--it's like a web, and in areas with an abundance of materials, the web keeps sinking deeper and deeper as it reaches the focal point or source, which is as deep as the supply is large and common. This is what gives a galactic economy balance and prevents niche sellers or items from devastating the state of the economy.

Anyways, back to the start of all this; my crystalline scale robe idea.... In a place where the choice material is incredibly abundant, such as Crystalsong, it could cost potentially as little as nothing and be made by hand by the owners/locals. That is why such an item will always retain a value relative to its location.