Hi
I already developed many apps like that so if you want good product without bugs then this will be the cost that i mentioned. One app will developed for user to view categories, view products, add to cart, place order, view order history, etc.
One web panel for vendor to add categories, add products with price and quantity, view active orders, view completed order, send notification, create login of driver, delete driver, assign order to driver, send notifiction, view user detail
One app for driver to view assigned deliveries, mark as complete etc.
Plz discuss if i missed something. We will aslo have OTP service which is 10,000 otp in just 2000 rs without any applying of gst. Plz discuss we will also save you server cost.