Build an Online Store

I am looking for a developer with experience on this field. There are plenty of requirements when creating this store. In short it should be similar to AliExpress/[login to view URL] but to have more categories so that different customers can choose their occupation and the products and services that are targeted to that type of customer is shown. The marketplace site is going to feature both products, digital products and services. When customer is buying the product he can send the vendor a message and a file that is attached to that product. Vendor can message back and also transfer files. Some external features such as these are required: Braintree as payment gateway Messaging between vendors and users Q&A – Questions And Answers on both product page + user profile - email messages when question is given Ratings Vendors can add various TAGS (up to 3) on the products. These tags show up in search. Search is limited by category. The category can be changed when performing a search. There is also browsable catalog of categories and tags that show the content. When reviewing the vendor the user can leave a private note for the main admin of the site. When searching the authorized and best reviewed vendors show up first if the product is the same. Verification, Authorization like in Freelancer (Plus Gold Member (these show up first in the Searches if tag is matched with the search terms) and Authorized mark that is granted by webmaster) Joining as a vendor is by a request only at the beginning. The vendor link proceeds to a landing page where is email address for the request to become on. Possibility to join with Facebook Connect (migration of info from FB) + Profile can be matched/connected later with a FB profile Vendors can retrieve the products from their ebay store. To obtain these features I was thinking of cs cart multivendor and elggg. (elggg can be substituted with social engine as well). If you have a specific shopping cart system that is open source and will obtain these features please make a suggestion. When making the bid please include all the prices of extensions, plugins, themes and other costs. Please list the costs of the components that you are planning to use in the project. The store will need some custom graphic designs too. The project is finished only when all of the features are working and are tested and there is no bugs and it is tested