I know exactly what you're talking about. Many electronic retail stores use bracket from Peerless Industry, which you can find on the internet for an amount substantially less than MRSP found in local electronic stores. For specific models, please click on the link below. Good luck.
http://www.peerlessindustries.com/allproduct_links/allproduct_walltv.htm
http://www.peerlessindustries.com/allproduct_links/allproduct_walltv.htm