mobile application

Hello, I have an app idea that works as a broker (mediator) between customers and suppliers. A customer should be able to to order any suppliers goods using the app according to some conditions that suppliers determine e.x the quantity. The suppliers should be able to receive the customer order and deliver it. - if he provides the delivery service - if the supplier doesn't provide the delivery service then we should ask the customer if he wants us to deliver the item according to our conditions. Our delivery service shouldn't be like Uber or Marsool apps, but in each district for example wiil be an employee who covers this district. This point because we wanna be specific for one product that is very popular, so the app is all about one product at least in this point of time. The customer will be charged for our delivery service but not for the suppliers delivery service. There should be a deal between us and the suppliers to get money from them (commission), so that we have to determine and save customers who make orders using our app. We might add a service that shows the customer where the driver is and show the driver where the customer is using share my location function. If we want this app how much does it cost us, what services do you provide, and how much time do you want to deliver it? Regards