I am seeking a script that users can post their websites for sale for a fee. They will need to enter data relating to their website and buyers must register to see all details of a given listing. Fee for basic listings and an enhanced fee for featured listings. An ideal security feature would be requiring the seller to upload a file to their server to insure they have control over the site. Preferably you have already done this or own such a script that you can sell me. Inexpensively please, the market is crowded and very difficult to compete.