Especially after your auction has ended ? And also during listing?
      Answer1:You cannot make a listing private after the listing is over.If your listing has a bid, you cannot make it private.The only way to make your listing private is to select the private setting while you are making the listing, prior to posting your item. Or, you can revise your listing before a bid is placed.
      Answer2:Two college students are doing something that has never been done before by putting everything you need to run a business in one place,they call it: Business Empire Magazine