info on magus system and system shop

no ordinary people can be on magus because they need a Lv-0 spell to initiate with mana something that is strictly kept under supervision

why can't I buy it from the system you ask simply because it's expensive because it's a free ( magus ) Class change also the system shop doesn't have anything it 'makes' them with enough 'Energy' only spells aren't made but copied because every spell has been recorded by the system to be able to be shopped for and they also are quite hard to understand like math