I read a book, or series, when I was a kid following a guy as he rose through the ranks of Magi. What I can remember is that the level of a mage's power was indicated by the color of their aura. For some reason, purple stands out in my mind. I also remember that, toward the end of the story, as the protagonist's power reached its peak, he managed to build a house/castle on the moon. I remember no names, and really no plot points.
Needless to say, trying to remember the name of the book, none the less track it down, has been frustrating. If anyone has a better memory than I, any help would be appreciated.
Afterthought; I read this in my early teens, or preteens, so it is not likely to have been released later that 2002. Also, it is likely that I got the book via Scholastic.