Slipknot's DIY suggestion is a good one. However, you may wish to consider the economical commercial solution that I am using with excellent results. I use a Target VW2 wall mounted turntable stand, but I replaced the top MDF shelf with an 18' x 22' x 1.25' slab of granite on cones.
I made sure to use the largest lag screws that would fit through the mounting holes of the VW2 rack, and made sure I hit the center of the studs in the wall. The granite weighs over 60 lbs, and the turntable adds 48 lbs., and I keep a bubble level on the shelf for continuous monitoring to make sure there is no sagging. After over a year, still no movement of the rack at all.
This was a tremendous improvement over the floor standing rack that I was using previously. You can see a picture of it at http://cgim.audiogon.com/i/vs/s/f/1122661578.jpg .
Anyway, that's my 2 cents worth.
Good Luck.
I made sure to use the largest lag screws that would fit through the mounting holes of the VW2 rack, and made sure I hit the center of the studs in the wall. The granite weighs over 60 lbs, and the turntable adds 48 lbs., and I keep a bubble level on the shelf for continuous monitoring to make sure there is no sagging. After over a year, still no movement of the rack at all.
This was a tremendous improvement over the floor standing rack that I was using previously. You can see a picture of it at http://cgim.audiogon.com/i/vs/s/f/1122661578.jpg .
Anyway, that's my 2 cents worth.
Good Luck.