User blog comment:ClariS/FEEDBACK! Cost Efficiency/@comment-1973463-20130203232210

gonna quote this here because it makes a lot of sense:

"The point of item efficiency is the comparison between just buying flat attack damage through BF swords rather than stacking your inventory with longswords which no practical person woud do."

There's no point in comparing the gold value of a 3000 gold item to a 400 gold item. When your gold efficiency values are based on BF sword being 116% efficient, I'd say they're pretty useless for any practical purpose.