
Make sure you have plenty of NP at hand, and usually, you can get help at the Battledome board. Just make a board, then request for help. Usually, peopel with many UBs and higher rarity items come, if not, wait. When there are enough people, start the quest, post it. You may get lucky, and the item may be buyable. However, if it is unbuyable, hopefully, somebody at your board will have it. You then trade.
At least, that's how I think it goes, from spectating.

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