Ben Brooks relates the cost of apps to the number of hours a person has to work to pay for it:
Here’s how to use this chart: pick the salary that most closely matches yours and the app price the see where the two intersect. This number you get is the amount of hours you need to work to obtain the dollars needed to purchase the app in question. Then ask these questions:
1. Do you gain more than X hours of value/time by owning this app over the course of the next year?
2. What about over the course of the next two years?
I don’t really agree with Mr. Brooks. It’s not as simple as, “my salary is ‘X’ so it will take me ‘Y’ hours to pay it off.” Mostly because people’s disposable incomes are not created equal. A 25-year old with no debt who lives with his parents and makes $50,000 a year has way more disposable income than a married 35-year old with 3 kids who makes $100,000.
I think realizing the relative cost of an app is more a case-by-base basis. For example, if you are a person who goes out to lunch everyday, you probably can’t really complain about even a $20 app. If you go see a movie in the theater every weekend, $5 really doesn’t set you back. If you struggling to pay the electric bill every month, a $0.99 app is a lot, no matter what your salary is.