Android Proof of Concept App

Looking for a proof-of-concept sales recording app. App should store all data in a database. expected tables would contain only very basic information. tables would be 'cards' 'items' 'orders' 'lines'. UI should allow for viewing of cards, select a card tro create and order, and add items to the order(in lines). Data should be persisted between app launches. App should be written using ORM or at least nice business object classes to represent the card, item, order etc in code. This is app will be a starting point for a protentially huge full featured app, so it needs to e well thought out and designed from the beginning. The code should be commented, and easy to read. No ugly spaghetti code. Need full source code.