Worth... I dont realy know what you mean...do you pretend to sell enchanted spears after creating or what? Thats the only thing that could give you some "profit" if you want to use the sould points.
If not, it would be the same if you just bought mana potions and do spells that dont use soul points to level up.
I literaly would not train your magic level directly. If I were you I would only take the weekly training wands and kill yourself in the arena everytime you can to keep spending mana points... I know it doesnt help you as fast as anyone wanted...but if you are constant you will keep a good mlvl acording to your level.