PHP/mySQL driven website click for details

Well, how do i say this, with out exposing the idea. I need a site done in php for a linux redhat box, in PHP. about 1/4 of the site is done needs to finished up and fine tuned. Here's what will need to be done. 2 sets of user groups buyers and sellers. Sellers need to be able to post a product, add/edit/delete/verify those products. Buyers need to be able to save a product in a user profile along with search for products recieving a list of related items. I know it's vauge so we can fine tune the price after the final bid is made