Also note that you get some spells from your priority selection* (i.e. if you put magic at priority 'A', you get ten spells (or rituals or preparations)). If you want more spells than what comes from the priority table, then it is 5 karma for each additional spell/ritual/preparation).
*assuming that you are using the default character creation method in the core rule book, or else the optional 'sum-to-10' creation method in Run Faster.