Functionality of Classified site

Here is the deal... We originally posted this project for complete design however all we need is someone to create the functionality of the classifed within the site we have created. Project Criteria: -Company must be based in the United States and willing to sign a development contract (protects everyone legally). -The site needs to have classified functionality added to and data base to be used must be MySQL... Information to login and complete the database on our server will be given. -Classified functionality includes register to sell and item, Any user can browse and contact sellers, Sign In to account, Search the categories (there will be 20 categories - No sub categories), we must be able to charge people a fee for selling their items whether through an emailed invoice or a prepay, I will post the design work we have done on the site is located at [login to view URL] so you can get the idea of what we want this site to do. -Picture galleries when searhed items come up must be of decent size... so you can actually see picture. -an example of the database functionality we are trying to implement and a site of similar functionality is www.harleys4sale.com. -On the home page all we want is a search for harleys. and our fees we charge to sell product on the classifed site. - there is 416 pixels X 363 Pixels on the home page to plug in this search feature. - the rest you can make it the same... however the only thing we care about are the background, header, and footer stay the same as long as the site functions well and looks good. We will supply the categories to the developer we choose. Please PM with any questions.... this is a relisting of our previous post because I believe people were misunderstanding what we wanted... so please rebid if you are confident you can achieve this.