Build a Website -- 2

Hello, I am looking to have a classified adds site built. This website will be similar to the website "[login to view URL]" but with some added features and personalized exactly to my liking. The website will allow users to post adds ranging from Car Sales to Real Estate to Last minute deals. I need a payment system which allows users to post adds in high priorty spots ie: "top adds" and "Front Page Adds" and a online payment system to follow. I am looking for a Online Chat system which will allow users the ability to chat with other users. Each user also needs to have their own page with different layouts for individuals compared to businesses. Their will be different forms based on the category the user is entering the ad in. I need someone who is competent in customized web development in order to fulfill all requests the way I envision them. Please use [login to view URL] as a starter as they do not offer alot of features I am looking for. I need someone who can complete this website in no longer than 3 weeks including all revisions.