Currency Balance Converter Android App

I need a basic android app developed which can convert different currencies. The app should also have an in-app purchase feature. The main purpose of this app is to convert gift vouchers into different currencies.

Key Features:
- Basic currency converter
- In-app purchase functionality for play balance conversion

Ideal Skills:
- Android app development experience
- Knowledge of implementing in-app purchases

I'm looking for someone who can deliver a clean, functional, and user-friendly app. Please attach your portfolio with similar projects if available.