I'll also add that it's nice to have configuration flexibility. When I first bought the SolidTech rack, I configured it as a single wide four shelf rack. By purchasing a few additional pieces, I was able to reconfigure it as shown in my previous post.
The columns are available in different lengths so you can create more space between shelves if desired. The shelf position on the columns is also adjustable.
These racks are generally available from stock. I was able to get mine in less than two weeks from ordering.
Below is what my rack looked like when I first put it together.