Destroyer Weapons Crafting Versus Buying

I've been looking at prices for Destroyer Weapons, and I've become a little confused.

Looking at materials costs, it seems like it may actually be potentially cheaper to purchase the weapon outright from another player than to have them crafted at Slaver's Exile myself?

Is that an accurate perception?

If so, how do players make any money on them?

Or are the rare materials one can get in player trades actually priced lower than one would expect by comparing the buy/sell from the NPC trader?

Can anyone shed some light on the monetary cost/benefit of purchasing versus crafting? Opinions as well as facts are welcome.

(Posted here rather than in Price Check because it's a bit more complicated than just wanting a quote on the item-- I've already looked at that and am now hoping for a more detailed explanation. )

It would be FASTER to farm/buy the mats then craft. But cheaper to buy if you find someone selling the ones you need. not much cheaper, but cheaper.

The amount of granite and iron necessary for crafting destro items is actually pretty easily farmable and can be done so in 4 hours at no cost after you equip a 55hp farmer, which can shave 10k or so off the cost to craft, that might explain some of the difference.

just made mine. someone has to craft them

with the price of diamonds on the increase I think its cheaper now to buy than craft---though I usually craft since I do a lot of dungeons and the end chests like to grace me with onyx and diamonds on average, leaving me with only having to get the granite and iron (easy to salvage from merch white weapons).
So it depends on what I have on hand when I am to the point of getting one.