Multiplatform Marketplace App Development

I want to launch a simple yet reliable buy-and-sell app that works on both iOS and Android. Users will be able to list brand-new, pre-owned, and even refurbished items, then choose whether the deal happens through local pick-up or postal delivery... (Budget: £20 - £250 GBP, Jobs: Android, App Design, App Development, Chatbot, Database Management, Flutter, iOS Development, Mobile App Development, Payment Gateway Integration, React Native)