Yeah I'm definitely not in any rush to get that. Hoping that they do one of the following before I farm for it:
a) Reduce the 6* ticket price.
b) Increase the Memory Crystal droprate for Memory Dungeons.
c) Allow Memory Stone -> Memory Crystal forging.
At the very least I'm waiting for the very rare Memory Dungeon campaign that increases droprates of Memory Crystals from 6 to 9 (I think).