Strictly speaking you don't need any gear on these servers beyond high AC/ATK/HP/weapon damage/2 clickies for dispells/specific proc and like maybe 1 consumable item, plus no other classes than shamans, necros, enchanters, clerics, and warriors. In Luclin, add in ranger to kill stuff quicker instead of necro. Maybe a druid for patch heals / DS, or a mage bot with coth in some locations.
So while it *is* valuable, it's not needed. All of the high market value items on TLPs are wants, not needs.
(also outside of the focus which can't be used in-era, it's really not useful in-era, literally no one should be having mana issues, and by the time it becomes useful, there's other focuses with the same effect.)