Design an app for my site (Integration)

Hello, I need a professional to create an app that can integrate with my website(instant publishing). The main idea is to get an app where i can post products from my company and others can publish in it as well (just as a clasiffied webpage), and automaticly it is posted in my web page(after a short verification of the information). It should be able to highlight a post if you, as a user, pay 5$ with a sign that displays something like(Unique, or special, or something like that). Highligh for my products of course is free for the company i run. One of the most importan functionality that i want to develop is to suggest complementary products for the product the customer just acquired. (Just like amazon) And important functionailities just as sending mesagges through products, following publications, scheduling appointments) There is a lot more i want to develop for this app, but this is like a 1st version. We are expecting to create a version 2,3... etc until the app is finished completely, but lets see how this goes. :) If you can create a professional app please bid asap. Thanks!