Catalog Website Database Driven

Our customer is looking for a designer to make them a Catalog Website for Hunting, Fishing, and Tools the site will allow the vendors to log in and post the photos, details, price etc. the Admin will then update the listing for viewing on the public portion of the site. All the data that the Vendors post should stay in the Vendor section and can only be changed by the Vendor, also the Vendor section can not be viewed by any other part of the site even other Vendors can't see other Vendors original postings only Vendors can see there own postings. The Database should be done in ASP.NET c# so all fields posted by Vendors should have the ability to keep or replace on Public site. When orders are placed the order will generate a list back to the Admin showing who placed the order but also show what Vendor the items should be ordered from Vendor information is private and should only be visible to Admin. The site should have email and Message system, Shopping cart, and the Database should allow Vendors to request new Categories so adding new categories and sub categories should be simple and to hide and unhide fields should be simple, the site will have up to 75 Categories and each Categories should have 3 to 10 Sub Categories but the site builder will only need to post samples to test the site because Vendors will be posting there own photos and descriptions so there will not be a lot of photos and descriptions to place. The site should have a back-up system, the site builder should place the site on the Domain we choose most likely it will be a Server based with SQL security. We do require the site builder to give us updates every 48 hours.