Everything that you desire already is locked up in a vault, and this can be opened to you in several ways. Sometimes, the universe will just give it to you, no questions asked. You will think of what you want, and some short or long time later, it simply shows up.
Yet, every wish has its price, and we do not always have the luxury of being able to determine the cost. Pacts can be written, offerings can be made, but there almost always will be a fine print of that we will be unaware of until the act is completed and it is too late.
Each action we take in the magickal sense has its cost. Be it time, health, and even sanity in some rare cases. The universe has its price, and we cannot act as though we are above this law.
Ultimately, to understand magick is to understand yourself. Your emotions, psychological processes, your triggers, motivations, etc. One can practice magick purely for the practical side, to change and morph reality into the shape that you desire it to be. But there also lies within this journey upon the left hand path the will to go far beyond the practical and delve into the deepest parts of your psycho-spiritual anatomy.
Yet, unless one can focus on the second side, and arguably the more important side, by which we can begin understanding ourselves and transmute the deeper parts of the subconscious. The side by which we can eliminate the pollution that has been fed to our egos since we passed through the birth canal and fully entered this world in physical form.
Maybe the ultimate cost of magick is to forget our fears and transmute ourselves into who we are meant to be.