When it comes to monetisation of your app you have the following options
- Sell the app to your client
This is the most used way, you create the app, and can sell it to your client for bigger money and make profit. You can add your client as moderator and he will not now how much you have paid for the app - (with reseller you get discount and extra system running under your domain).
- Put ads inside
You have the options to put AdMob and StartApp Ads inside your app
With adMob you have banners, with StartApp banners and interestials ads.
This is suitable if you expect your app to have a lot of users.
- Sell products and services
In Mobidonia, there is eShop, so you can sell your own products or services.
The payment goes through paypal.
- Sell the app on Google Play and App's Store
You can put price on your app. The money goes to you