[callydrias]

I agree with Moo. I've never seen a monitor stand that can handle that much weight in the cantilevered configuration you want. It would either have to have an extremely heavy base or be bolted to your chair/floor.

My first thought was MyPCE (which someone mentioned already). They might be able to do a customer 4 monitor setup for you.

Alternately, if you find a stand that works for 2 monitors and has adjustible height, you could put one on either side of your chair with the monitors of one above the monitors of the other.