I am using AndroidBillingLibrary for purchasing. But I don't know how to get the price of purchase (in-app item) in code. If it possible using the library, because this library based on In-app Billing API version 2? I saw that it is possible in API version 3 link
This is impossible. But I implemented in-app Billing version 3. This is not so hard, there is a great and very simple documentation link. Also Google provide a sample which anyone can download and use how to install sample