Perspective on item prices
So I just sold a 4* sword in under 12 hours on the auction for 200k. Faster then I thought. So then I decided to do some math...
At 6k/100 energy, it costs ~96k Crowns to make a 5* weapon, plus recipe/heat costs.
4* is ~40k + recipe/heat
So, are the additional costs of my 4* sword really worth 160k crowns to someone? What value is put on time/heat? *shrugs*. Somewhat rhetorical but figured I'd post it.

Does that ~40K include the energy/crown cost of the lower-star versions of the weapon required before reaching 4*?
4* and 5* items are also super-rare now because they auto-bind on crafting, which may add to the perceived value.
The sword probably fetched a high price since it is one of the few 4* swords that exist that are not bound due to the 5/17 patch. So when a 4* sword goes up for auction and it is the only 4* sword, it'll receive a lot of attention and likely result in an inflated price.
yes the number was cumulative, might be off by a few K but I was just after a rough figure.
Rare or not, when you can make it yourself for substantially less... *shrugs*. The hardest part is just getting the recipes. Tempted to sell my unbound Hail Driver now, curious to what that'd fetch now lol.
It's also about rarity. Right now you can't get a lot of four and five star weaponry in the auction house and some people find that appealing.