Not quite. Cost is directly affected by the efficiency of the energy producer when converting energy to matter. Now, we have produced matter from energy. That is the basis of particle accelerators. You add energy to a subatomic particle so that when the energy is released through a collision with another high energy particle new particles are formed. The problem is that these reactions hardly ever produce any stable particles at all. Physicists analyze the decay patterns of those particles to find out what was initially produced.
Matter/energy equivalence just means that anything with mass contains massive amounts of energy. Fusion reactions typically release less than 2% of available mass, and they are second only to matter/antimatter in conversion efficiency. Matter/antimatter reactions release all energy contained within the mass of the particles.
To create something even similar to UU matter(in other words, a stable form of a massive particle)the energy required is beyond anything feasible. 90 trillion Joules, as Riuga said, is just how much energy is in a gram of matter. Increase that several orders of magnitude to get an idea of how energy would need to be expended to create one gram of stable matter.