You can buy Grand Soul Gems in Oblivion from the following reliable sources:
- Mystic Emporium in the Imperial City Market District : Vendors Aurelinwae and Calindil regularly sell Grand Soul Gems, both empty and filled. Their inventories refresh, so check back often. Prices are usually under 100 gold for empty gems and around 300 gold for filled ones
- Mages Guild Halls : Most Mages Guild merchants across Cyrodiil carry at least one Grand Soul Gem for sale. Chorrol’s Mages Guild is a notable location with display cases containing them, though some are behind very hard locks
Additionally, you can find Grand Soul Gems by:
- Exploring ruins and dungeons such as the Arcane University, Drakelowe, Nornal Ruin, and Squandered Mine, where they appear in locked display cases or chests
- Defeating mage enemies and necromancers, who sometimes drop Grand Soul Gems as loot
- Using lockpicking skills to access locked containers that hold these gems
If you want a guaranteed purchase, the best bet is to visit the Mystic Emporium in the Imperial City or check Mages Guild merchants regularly, as their inventories refresh over time. For curing vampirism, you can temporarily take a Grand Soul Gem from the witch’s basement and return it later, which is a special case
. In summary, buying from the Mystic Emporium and Mages Guild merchants is the easiest and most consistent way to acquire Grand Soul Gems in Oblivion.