IAB v3 Stuff ... v2 Stuff ... Google IAP Android

How to implement IAB v3
http://developer.android.com/google/play/billing/billing_integrate.html

but if you are using sharedUserId, you will be stuck with IAB v2
http://developer.android.com/google/play/billing/v2/api.html

Either way your Android application will need a custom list view
http://www.ezzylearning.com/tutorial.aspx?tid=1763429

ListView, you remember this good old fashion Android UI widget?
http://developer.android.com/reference/android/widget/ListView.html

Now, once you get through all that then you start digging into the API
http://developer.android.com/google/play/billing/v2/api.html

You will have errors. They might be this error about developer keys:
http://stackoverflow.com/questions/11068686/this-version-of-the-application-is-not-configured-for-billing-through-google-pla

A typical in-app billing implementation relies on three components:

• A Service (namedBillingService in the sample application), which processes purchase messages from the application and sends billing requests to the Google Play in-app billing service.
• A BroadcastReceiver (namedBillingReceiver in the sample application), which receives all asynchronous billing responses from the Google Play application.
• A security component (named Security in the sample application), which performs security-related tasks, such as signature verification and nonce generation. For more information about in-app billing security, seeSecurity controls later in this document.

You may also want to incorporate two other components to support in-app billing:

• A response Handler (named ResponseHandler in the sample application), which provides application-specific processing of purchase notifications, errors, and other status messages.
• An observer (named PurchaseObserver in the sample application), which is responsible for sending callbacks to your application so you can update your user interface with purchase information and status.

In addition to these components, your application must provide a way to store information about users' purchases and some sort of user interface that lets users select items to purchase. You do not need to provide a checkout user interface. When a user initiates an in-app purchase, the Google Play application presents the checkout user interface to your user. When the user completes the checkout process, your application resumes.