I know you said you don't mean for regeneration, but for Necromancers regeneration is actually a huge help. Since they can't wear a Fungi, the next best tradeable item they can use is the (
much more expensive):
https://wiki.project1999.com/Zlandicar%27s_Heart.
But as Jib noted, for Int casters you want mana regen, not HP regen (ie. you want Flowing Thought or a mana stone/robe). Almost all FT gear is No Drop, with only two exceptions:
https://wiki.project1999.com/Choker_of_the_Wretched
https://wiki.project1999.com/Crown_of_Narandi
Just like the heart though, both of those are
much more expensive than a Fungi. There's nothing even close to a Fungi in power for Int casters in that price range.
P.S. Specific classes have key powerful items that
are under a Fungi's cost though. For instance,
https://wiki.project1999.com/Burnt_Wood_Staff for a Mage, or a
https://wiki.project1999.com/Goblin_Gazughi_Ring for Enchanters.