Conjuration is very easy to level without needing to spen thousands on a trainer.
Level enchanting to 100 (or 80 at least), enchant some gear with 25% fortify conjuration enchants, cast soul trap on a corpse over and over again.
Even without the enchants, it doesn't take too long... provided you're not a vampire trying this during the day. I never get the cost reduction gear until later in the game.
True, I would at least enchant some cheap gear with magicka regen in several slots, since that enchant is easy enough to find (practically every enemy necromancer or conjurer is wearing black/necromancer robes with the enchant on it). It makes the process faster if nothing else.
Playing UMvC3, Far Cry 3, Black Ops 2. PSN: Entropy19