Mobile App Development

I'm in need of a competent mobile app developer who can efficiently build an E-commerce app for both iOS and Android platforms. The primary features the application should entail are in-app purchases and live chat functionality. The ultimate goal of this mobile app is to facilitate E-commerce.

Ideal Skill Set and Experience:
- Proficiency in iOS and Android app development
- E-commerce app creation experience
- Capability to integrate in-app purchase features
- Proficiency in adding live chat feature
- Good understanding of UX/UI for seamless shopping experience

Please provide a rough timeline for the project along with your bid. I look forward to your proposals.