These are the resellers (most of the time). I bought sheetmetal off of Ebay by using the "best Offer" link. The guy says in the auction that they will be dropped shipped to your business or home address by the manufacturer. He takes the order, calls the company, then you get your parts. All he does is make money on his discount.
Make sure that you have him call the manufacturer first to make sure that the parts aren't on back order if you need them right away. I had to request a refund on a 3/8 e-body fuel pickup, because the company selling it didn't even have it in stock. I ended up getting it later for $55 after asking if it was in stock first.