It is really bad even on the high end. Rank 9 battle armor, rank 10 refines, very high orange init purify, rank 10 headband charm are all far more cost effective. (And if you care more about general stats and not just stacking init... rank 10 charms and good purifys on all equipment slots.) After you've done all that... breakthrough pills becomes a "good" deal, simply becuase you don't have any choice left. The single ninja in question will be past 50k power by that point.