I've never seen one. I would think anything strong enough and stable enough to do the job would be heavy and expensive.

Just got a new 50" plasma that was mounted high on a wall up about 6 or 7 feet at bottom of the set. This set weighs about 110 lbs and therefore mounting is a two man+ job! The mount that we used basically works like a hook to picture frame type system albeit much much sturdier. I was alot more concerned with making sure the mount was securely/safely attached to the wall ie into the framing studs. Lifting although not a breeze was managable with two when staged from the floor to a table and then up to the mount itself: where exactly is your problem?