There are a number of websites that sell these types of mounts and shelves. Not allowed to write actual full website addresses on this forum so I'll offer the following:
avmountsonline
standsandmounts
racksandstands
omnimount
You could also try your local Circuit City.
avmountsonline
standsandmounts
racksandstands
omnimount
You could also try your local Circuit City.