If I were to recommend my top five options that give the most bang for your buck, Id probably advise you to pick up the following: Sunforger is impressive even with budget spells
Nonetheless, it bears mentioning here due to its ability to place an Archon of Cruelty or Emrakul, the Aeons Torn on the battlefield as early as turn four
TCGPlayer currently shows Jace, the Mind Sculptor's Bloomburrow variant at a $261.98 market price at time of writing.
Aurora offers up a number of helpful effects, alongside some solid stats to boot
It's a low opportunity cost card that can help sink excess mana into a great static effect, with level three offering an alternate win condition in the same vein as Young Pyromancer without the same level of investment or vulnerability to common removal spells
I like to think these cards do a good job of explaining why we rotate out mechanics in Magic