Here was my design... I don't have pictures of it, I thought I took some, but if you really really need the pictures, I'll take my monitors off the posts and photo them for you. You'll have to wait until after the weekend though.
Essentially its 2" angle iron, which part hangs over the top of the desk, and part over the back fo the desk, with 1/2" holes. The console table (steel) that I built has 1/2" threaded holes, to which the 3/4" half in bolts screw into. No nuts necessary. The upright is 1-1/2" square tubing, and while it doesn't show in the drawing, on top of that is 1/4" plate about 6" square. This is all welded together. Then a 6" square pad of rubber sits on top of the metal, and the monitors sit on top of that. I have two monitors per side, one on top of the other, and these posts support it just fine. Because they are bolted to the steel table with four bolts (two on top, two in back) and my welds are decent, they don't move at all. You can push hard and make the monitors move, but bumping the table they are rock solid.