Do you get the value back, when you build an app?

Hey everyone!

I am trying to understand the application development process, like how much time and money does it take to build an app on a certain type of platform. So for I have 3 questions -

1. What type of app are you building (or have built during recent times)?
2. Which platform or tool did you use?
3. How much time and money did it cost?

It would help me understand the process if you'd answer.

Thanks in advance!