Introduced in TWW there is a required PVP reagent when crafting PVP gear.

For example:
2H Staff:
https://www.wowhead.com/item=225369/algari-competitors-staff

Needs this required reagent that is added by player:
https://www.wowhead.com/items?filter=243;255;0

These can cost between 500-2000g and some recipes require 3-10 of them so they significantly impact cost. Craftsim at the moment ignores these and probably thinks they are optional reagents.

hm yeah this needs to be considered

But it seems they do appear as optional slots in simulation mode and it should consider prices of optional reagents
need to test this
and probably check if I can identify such slots and mark them as required