>The issue is still the same. You are asked to bid on an app that contains 100 widgets. You know that you have already built 25 of those widgets before. Now do you bid in a way that you account for building all 100 widgets from scratch, or do you make a bid for building 75 widgets and giving away 25 widgets for free (and there is also the in-between approach).
>
>Now here is an interesting question: Let say you are working on a project where you can bill them by the hour. You wake up in the middle of the night and lay awake for 1.5 hours solving a very difficult widget implementation. When you get to your computer the next morning it takes you 30 minutes to build the widget. Now do you bill for 2 hours or do you bill for 30 minutes?

There's an old story about a peasant who came to a lawyer to file something against his neighbor - cow in corn or something - and the lawyer typed a sheet of paper in five minutes, and charged $100.

The peasant paid, but asked "what exactly costs $100 here?" The lawyer replied "the paper is $0.01, the office rent for five minutes is $0.02 ..." and the total cost came up to about $1.00. "So what's the $99 then?" "That's the cost of me knowing how to do it in five minutes."

I'd charge one hour, but made damn sure that my hour has a decent price.