Now your talking like a shooter. The only missing part is where you have to explain to your wife why you "need" a $600 gun to avoid wasting $25 worth of old powder? I would try something like exponential value growth of the investment in the original by what it could have earned in an S&P 500 index fund over the same period, and equate that to its current value. Avoid answering questions about the relevance of the comparison.
Wow, UncleNick, that is some expert advice. Did it work for you?