It is extremely likely that House Corrino maintained a large spice hoard.
Being wholly dependent upon the spice for interstellar travel, the Spacing Guild likely maintained a large spice hoard.
Being dependent upon the spice for the creation of Reverend Mothers, the Bene Gesserit maintained their own spice hoard. Shortly after Leto II's death, it dwindled away to almost nothing before the sandworms and spice reappeared on Rakis.
Leto Atreides IIEdit
During Leto's reign, melange was strictly controlled. As a result, the hoard's value as currency was said to be incalculable. Only the God-Emperor knew where the hoard was kept. Not even the emperor's last majordomo, Moneo Atreides, knew its location. Over the 1500 years after Leto's reign ended, the legend of the "great spice hoard" passed into myth.
The hoard was eventually discovered by a Fremen girl and a Bene Gesserit. Sheeana Brugh and Reverend Mother Darwi Odrade discovered to hoard hidden in the Shield Wall, after being led there by a sandworm that was said to contain a pearl of Leto's consciousness.
With the hoard, Odrade discovered several messages inscribed by Leto on the walls in Chakobsa, messages he intended for a Bene Gesserit to find. The hoard itself, while still relatively large, was not considered to be a priceless fortune by this time. After Leto's death, the Bene Tleilax had developed a way to successfully synthesise melange. Its value, though still very high, had by now dropped significantly.
The hoard of melange, fabled for its immense wealth for so long, was successfully removed from the Shield Wall by the Bene Gesserit and distributed between the Bene Gesserit, Bene Tleilax, and the Spacing Guild, to be added to their respective stockpiles.