B2C Comparison of Prices MultiStore Plataform

I am looking for a develloper capable to create a site B2C where the traders will be able to announce its products for the final consumer and these products are grouped in categories and listed and commanded by the price in increasing way. The website must be composed of 3 interfaces: 1 - Destined to the final consumer, who will be able to look the desired products and to compare the prices (front end) 2 - Destined to the traders, who will be able to announce its products and to change the price of the products with update in real time. (back end for tranders) 3 - Destined to webmaster, that it will be able to create or to exclude categories, pages of products, to block advertiser and etc. (back end for administrator) Only the administrator can register the traders, because the service to them will go to pay monthly fee to be able to use the service. Only administrador can give permissions to traders be able to liberate the access of the trader to the publication system of announcements. An example of site of this type can be seen in: [login to view URL] The service must also include webdesign and the system php / mysql with friendly interface and visual clean. Each advertiser (trader) will inside have a proper page of the website where they will be able to list all its products and to fill its data of contact to be found by the consumers. The structure of the website must be seo friendly. The site must have areas destined to the insertion of advertising in formats 160 x 600, 300 x 250, 336 x 280, 468 x 60, 728 x 90 and that they could be to be activated or to be disactivated through the panel of webmaster. Site needs to be connected to the social networks like (Google +, Facebook, Twitter, Orkut, and others). The site will be used in Brazil, but it could be developed in English and later translated for Portuguese (I can do that). Characteristics of design: simple and functional with white background, with black text (verdana, arial), layout with collors like yellow, green, blue and red are welcome. For more information on the project, sends messages.