I think two important metrics are being left out of the author's perspective: 1. What value do I assign to my personal free time? 2. Does my purchase have the

I think two important metrics are being left out of the author's perspective: 1. What value do I assign to my personal free time? 2. Does my purchase have the ability to save me time? For instance, a cup of coffee will cost me 15 minutes of my salaried time PLUS 15 minutes of my personal time (to drive, order, pay, etc). However, perhaps I am a writer and the coffee and coffeeshop environment will help me accomplish 2 hours of writing in 90 minutes. Then the whole thing is a wash.