Classifeds/Auction style software needed

I need a classified/auction style software. These are some of the requirements. 1- user must have a "My Account" section where they can see messages from buyers, option to answer, purchases, selling tools. Similar to "My ebay". 2- user will be able to sell their products, upload pictures and option to by extras to enhance their listing. 3- buyers will need to register to buy or bid on an item. 4- The administrator interface should have options to create specials for listings, add advertisement via banners or AdSense. Be able to email all users. 5- Option for "agents / sales reps" to be able to add products on behalf of other customers. I will give more details via email or chat. We are open to ideas. Thank you, Oliver