Craigslist style driven website

We are looking for someone to create a website with the same functionality as Craigslist.org. Obviously, we need the design to be unique with no copyright infringements. We need all functional aspects of site, including the search functionality, categories, user accounts, full admin access, etc... We would also need advertising space to be considered in design, this will be added later when traffic is increased. Please submit a mockup design if possible. Include in detail the project steps and platform being used. The site topic to be sent once project is awarded. This site will apply to 15 states and others state could be added at later dates. Thanks