Mage Tier 1 – Arcanist Regalia
This tier drops entirely in Molten Core. Some pieces are BOP while the two pieces that drop on trash are BOE so you can check the AH for a couple of the pieces.
Arcanist Belt (BOE) – Trash mobs
Arcanist Bindings (BOE) – Trash mobs
Arcanist Crown – Lucifron
Arcanist Boots – Garr
Arcanist Gloves – Shazzrah
Arcanist Leggings – Magmadar
Arcanist Mantle – Baron Geddon
Arcanist Robes – Golemagg the Incinerator