Welcome Chris. I am going to order some platforms from you soon. Meantime, I have a product suggestion for you:
Did you ever think about drilling some of your larger platforms for those large threaded rods (I have some that are I think 5/8" and around 36" tall). Sell them in batches of 3-4 finished, ship them flat, and we go to home depot or something and buy the rods. One could spray paint the rods in a flat black (or leave them plain), and have a very sweet looking, solid, and reasonably priced stereo rack. 
Here is a better idea


Here it is.
Sorry it took so long but I have been very busy.
I didn't like the idea of threaded rods (cheapens the rack) so I made Maple post.
This is the unfinished version.
This rack will come unassembled for shipping purposes and it will be easy to assemble.
It also weighs around 200 lbs.
I think the weight and thickness of the shelves will provide both great isolation and immunity from transferring vibration (sytem and electrical) through the system.
The result: use brass cones (cone point into the wood) between the component and the platform and voila the best of both worlds.
I learned that from JoshK
I can make this with more or less shelves
I will post pics of the finished Rack in a few days.