Cross-Platform Bus Booking App Development

I'm looking for a skilled developer to create a bus booking app for both iOS and Android platforms. The app should include:

Core Features:
- Ticket Booking: Users should be able to easily book bus tickets.
- Bus Seat Layout: Users should be able to select bus seats.
- User Reviews: Integrate a review system for users to share their experiences.

Payment Integration:
- The app must support integration with payment gateways.

Ideal Skills & Experience:
- Proven experience in developing mobile apps for both iOS and Android.
- Strong background in API integration, particularly with payment gateways.
- Experience in implementing ticket booking systems and user review functionalities.
- A portfolio showcasing similar projects, along with demos or working prototypes.

Please provide your cost estimate and any relevant demos of your previous work.