Create a Marketplace for Ads

Hi, I need to create a website which exactly resembles the functionality of [login to view URL] but I want a different design with few major changes. It is a website which lists down all advertisements available, displays map location and other information. Enables messaging between logged in users and vendors and payment processing via Paypal and other gateways. It also enables inventory management for vendors and buyers. I recommend you to have a thorough look at the website before you bid. Wouldn't be difficult for someone who's good at PHP and Databases.