Used Car/Bike Selling Flutter App Development

We are looking for a car/two wheeler price comparison app development. It should work like policy bazaar for comparing policy prices. You will have to first show me APIs. I'll pay for APIs if you purchase. On this app, people will fill the details of their vehicle and submit. Our app will calculate price from all other marketplaces and show it to users. If buyer will like to buy any new or used car or bikes, scooties, then also will have enter their choice and app will show results from other top markerplaces also, user will have select any of those. There should an option for users to post their vehicles for selling online. Source code of the app will be our property. There should be a single app, where buyers and sellers will have to register. There will be an admin panel which will control all the activities of the apps. Admin should be able to see sales, number of registrations, cashback, promo codes, push notifications, customer support etc. There should be a customer care panel, where user will be able to connect to our customer care on whatsapp. Once user will send any requests to customer care, a ticket should be generated. Backend should be on firebase. App should be developed on flutter. Admin panel should be on Php. There should be Google maps api integrated. When user will install our app, it should ask their current location, when user will allow location permission, it should be seen on user's home page always on top like it shows on food delivery or car booking apps. One mobile number or email i.d can be used only once for registration. There should be subscription fee for posting any vehicle to sell. User should see the free option or paid one should be optional. You will have to upload the app on Playstore and app store with signing key and handover the key to us. You project final payment will be made only after removing all the bugs and making app live.