I think this is the wrong way to go about it. Jewelry stays in the store forever, ampies do not (and other consumables do not). My goal has always been to clear out ampies, manyu, affection items, and coins every shop period (so far that's been about every two whaleship cycles). If I have time to farm, I'll buy the next cheapest jewelry piece. Buy dragons and those bloom birds as need dictates.

As of this cycle, I mostly did the above but left some affection items and did some farming for the earrings. Next cycle, I'll probably be able to finish off the affection items and get the repeat necklace.