Cross-Platform Shopping App Development

I need a comprehensive shopping app developed for both iOS and Android platforms. The app should include:

Core Functionalities:
- Product browsing
- Shopping cart
- User reviews
- Fully functional payment integration
- Delivery system
- Migration capability with other websites

Payment Methods:
- Credit/Debit Cards
- Mobile Wallets

Ideal Skills and Experience:
- Proven experience in developing cross-platform mobile applications
- Strong knowledge of payment integration and security
- Familiarity with delivery system implementation
- Experience with website migration
- UI/UX design skills for an intuitive user experience

Looking for a developer who can deliver a robust and user-friendly shopping app within my budget. Please provide examples of previous work and relevant experience.