If you are trying to make gil of the board..really just look for what has relatively few listings and go with that.

And generally ignore the topmost/newest stuff. There will always be people who need level 10-50 gear. Not a big haul but it adds up. Alternatively just sell materials at a markup (you can buy many from NPCs and just resell it for profit).

Unless you are trying to make millions real fast in which case, crafting isn’t the way.

You are much better off doing treasure maps and selling drops…