Some of the furniture that Horchow and Nieman-Marcus (and a number of other retailers) sell is manufactured specifically for them and only for them. So even if you knew who their vendor is, you might still not be able to purchase a like piece directly from the manufacturer.

If you look about it Restoration Hardware, Pottery Barn and most catalog companies do not reveal their manufacturers and even if you could find our who they are I doubt very much if they would sell to you are any other retailer. These retailers can give a manufacturer substantial volume and they are not going to risk their rath for a few sales to individuals or small retailers.