Multi-monitor stands are crazy expensive IMO and it really annoys me. I built my vertical stand myself and it wasn't too much trouble. When I go to my 7 monitor setup (still vapor ware until I actually spend the $$$) then I'll definitely have to build it, haven't even seen anything like what I'm after.

One thing that I got hung up with on my first stand was making it all swively and tilting. The reality was though that I set it in position and never touched it again. So for my 7 setup I'm going to design it statically for my purpose. This makes things MUCH simpler and you probably won't miss much. If you have access to a welder and associated tools then go for the make-your-own, save some money, and get something that truly fits your needs.