I think what you are talking about is using base rock. Base rock is simply dried rock that has no bacteria living on it. Live rock is base rock that has been colonized by bacteria that are part of the nitrogen cycle that keeps your tank running. Curing is for live rock mostly - usually there will be die-off from the live rock (bacteria, creatures, etc) that occurs during shipping. You want to cure this rock to make sure the dead material does not affect your tank.
To save money many people buy base rock (which is much cheaper) and a small portion of live rock to "seed" the rest of the rock. This is the method I used with my tank. In time the algae and life from the live rock will spread to everything in your tank. You can use the porous rock from the pond & garden store, but just make sure it is clean and will not leach chemicals, etc into your tank.