Build a Website plus associated Android Apps

I am looking for a solution to aid in direct sales. This involves sales force using Android devices to log order and deliver, customers who can use Android (later iOS) apps to place orders that would be routed to a sales person for fulfilment and a central inventory, order and customer relationship tracking system (web-based) that can monitor and track activity across multiple sales people each of whom has a dedicated Android device. The solution should have 3 parts: Phase 1: 1. A backend website to update overall inventory, customer information including order and interaction history. This should also be able to track order position by sales device. 2. Each sales person will carry some inventory and a device. The individual inventory should be reflected in the device. All customer data should be accessible from all the devices. Each device should be able to query neighbouring ones for inventory in case they need more of a certain product. The Sales app should be able to do invoicing, totals, and have a product catalog that can be populated from the central database. For this part, please see Cuke App on Play Store. Something similar is what I have in mind with the ability to sync multiple devices (many sales people) to the same inventory and customer database. Phase 2: 3. A customer-facing app where the customer can see the available product catalog without waiting for the sales person. He/she should be able to place and order which should go to a sales person based on business logic. The sales person will then be able to fulfil and collect payment and record the sale in his/her app. 4. Credit balance/integration with online wallet systems to make the payment process cashless at the customer's side. Please quote pricing separately for Phase 1 and Phase 2 and if you will have any price reductions if they are awarded together.