Is that something you generally miss in your life, "really dense stuff"? Seems unlikely someone would justify "one of the best purchases I ever made" with "it's really dense".
Or maybe I just don't see how something really dense could be useful except if you need something heavy but don't have a lot of space available.
You can make very awesome things out tungsten or tungsten carbide. I think, I would like to have a cube as well, to be inspired by the potential of it ...