act 3 normal, so about level 18? I don't know the level requirement but the blacksmith in Act 3 sometimes sells them. also the armor vendor in act 4 normal has them sometimes.
to be clear, i'm speaking of the the magical types that can't be used for runewords but still have 3 sockets. i haven't seen vendors selling 3 socket plain helmets (i don't think its possible)
This post was edited by NatureNames on Apr 27 2023 01:43pm