Artflakes Type of Marketplace Website

I am looking to get quotes on the following user story for a multi-vendor website which will allow vendors to sell both physical items as well as digitally downloadable items. This user story and post has been our together as preliminary test to get an idea for budget. Bidders will be contacted after review process. User Story: Seller Requirements * Sellers can upload product and product images. * Sellers can upload logo * Sellers can set pricing * Seller will have their own page to showcase their product * Sellers can write and update a profile description * Seller can select different shipping options. * Seller can select to ship product themselves or have admin fulfill the order * Seller can promote either each individual listing or their page via social networks (FB and Twitter) * Seller most have their own portal to for login * Seller can add and delete inventory Buyer Requirements * Buyer can browse products by category or by entering text in a search field text. * Buyer can filter results by price or sub-category * Buyer can purchase as either a guest or as registered user * Buyer can purchase using PayPal * Buyer will receive email confirmation of the order Admin Requirements * Admin must be able to review sales * Admin can set commission levels of resellers * Admin can see payments made to each vendor * Admin can have payment sent to the seller instantly minus the commission (check PayPal commission payments api) * Overall site UI should look and operate similar to [login to view URL], [login to view URL] or [login to view URL] The website can be custom coded or out of the box just as long as its clean and works well. I would like to keep with either Magento or I know there are number of different websites that offer multi-vendor extensions or plugins. If you or your company has experience with one please let me know and explain it your proposal. The website must load quickly yet offer a decent amount of resolution so customers can see the product in detail. All those who are bidding on this project must have samples of you work. Thank you