Native Mobile App for Quotations and Invoices

I need a native mobile app developed for both iOS and Android platforms. The app should allow users to:

- Create and store quotations
- Link quotations to invoices
- Connect to web services for data synchronization

User authentication should be via email and password.

Ideal Skills and Experience:
- Expertise in native mobile app development for iOS and Android
- Experience with secure email/password authentication
- Knowledge of integrating web services for data synchronization
- Strong UI/UX design skills for a user-friendly experience

Looking for a developer who can deliver a robust and efficient app within budget.