Dont think of price, think of cost per use
This is completely backwards.<p>Always think in absolute dollars and not in rates. $1000 is $1000 whether the cost per use is pennies or tens of dollars. Thinking in terms of rates is how people would fall for predatory installment purchases in the old days (you can have a new computer for just $2.5 a day!)<p>The other obvious problem is looking at cost absent of a market. It&#x27;s not just how much it is worth it to you, but what the competition is offering it for. I personally pay less than $400 a phone and keep it for over three years. Paying $1000 for a phone just two years is not an improvement.<p>Edit: I spoke very dogmatically above. Using rates can be OK in certain situations where the analysis becomes equivalent to using absolutes, but it&#x27;s not at all rare for rate analysis and absolute analysis to differ, and people make the mistake of using rates there. You will never, ever, go wrong by looking at absolute amounts, though - and it&#x27;s usually the <i>easier</i> way to analyze.<p>In my engineering undergrad, Engineering Economics was a required course. I remember a fellow student said &quot;I often return other engineering textbooks to get some cash, but this book is more useful than most of my engineering ones.&quot; Decades later, I can say he was definitely right. All too often I see engineers making poor financial decisions based on heuristics when they&#x27;re quite capable in doing the (simple) math. But a lifetime of being exposed to flawed ways of thinking of money provides a convenient shortcut.