You can, but they aren't as cheap as I had been hoping. If I recall correctly from when I searched a few years ago, they are about 30-50% the price of mined diamonds. Much cheaper overall, but not at commodity levels yet. I had been hoping that they would be cheap enough to buy a few hundred, then hand them out as party favors to weird people out. At some point, I hope they get there.

Rubies, on the other hand, are ridiculously cheap. If I feel like picking up another hobby, learning to cut gemstones from bulk corundum could be rather fun.