If you are trying too stay super budget then you got it. it seems like you can use your deck with the budget you've created, but if you are looking to upgrade then here are some ideas that may or may not take you out of that budget range.
Leonin Warleader Shield Mare Grim Initiate Lightning Stormkin can be removed from the deck for they do not hold any real value to the deck it self.
Spellheart Chimera is not a bad card but can have
Crackling Drake and
Enigma Drake along side it. Jeskai also happens to be a more spell slinger heavy deck to where you could remove a good portion of creatures to just add support creatures like
Young Pyromancer Monastery Mentor and
Saheeli, Sublime Artificer. There are a few moe like them but the just give you a large board state for casting a few spells. certain spell support helps as well like a
Jace's Sanctum and
Baral, Chief of Compliance these will help you cast larger spells more quickly. I hope this helps, if you would like to transition to this type of deck check out my deck named Kykar Spell Slinger. it is a Jeskai spell deck.