need a clone made of Flippa.com

All functionality needs to be cloned, and a similar design should be created as well.

Must have a backend admin area where I can edit users listings and settings.

Website must be coded in 100% valid, tableless XHTML and CSS. Tables can be used where appropriate, but not everywhere. Must use clean separation of CSS and XHTML markup.

I would like to make the listing fees FREEm and instead offer upgrades to the listings, such as BOLD listing for $10, or HIGHLITGHED listing for $15, etc. So for larger sites, like $4000, instead of paying 5% ($200), they would only pay $10-$25. So PRICE will be a large factor. Also like said a nice design will help too!

Project must be completed ASAP.