Classifieds Site

We are looking to get a classifieds website created. Its your basic website of that sort, the site will have the following page types: List(with what you see is what you get functionality), Search, Browse, Search Results, Item Description, Item Center(users can add watched items, and see items they currently have for sale/buying), Message Center, Profile, Preferences, Admin Center(with CMS for categories and user stats), payment processing for purchased upgrades, Advertising management. You cannot use a script, this site will need to be coded from scratch.(You can use some other code, but you can't just install some template and call it a day) There is already a mock-up of the design and the categories. But you'll have some freedom in website design. Essentially there are a lot of subcategories. The website is very structured. So as an example, lets say a person is listing something. They go down the main categories, down to say category "XYZ", then they can select attributes for their item from different lists: List1, List2, List3, List4 etc. So in the database we would have: item title/description/user stuff, XYZ, List1(Option1), List2(Option3), List3(Option7),List4(Blank) The person/company bidding has to be based in United States. Language wise, fairly open can do the basic PHP/MySQL or .NET/MSSQL. Overall I would say the project is very simple, but its pretty big.