Rank 4 magical beasts' bodies were valued thousands of Credits.
Each of their body parts was a rank 4 material and the market of the Royal city could never have enough of them.
The main reason was that those materials were rare: there weren't many cultivators able to fight those beasts, and those that could weren't willing to spend their lives as hunters.
Most of the supplies of rank 4 materials came from the cleaning operations of the Royal army but those missions were linked to the personal benefits of the Royals, they weren't aimed to gather the materials needed for the various professions in the capital.
Only the Hunter's guild would accept to hunt specific magical beasts if the right price was added to the value of their targets.
The Shrinking elephant, or more precisely its tusks and trunk, were needed by the guild of the inscription masters.
They were the best materials for the creation of strong inscribed weapons that suited their characteristics, like spears and whips.