Solid build, loving the budget idea. Just some suggestions on neat cards that stick within budget:
Ayli, Eternal Pilgrim ($0.81) - a 2/3 deathtouch for 2 mana is solid without help, plus if you have 30+ life you can use it to
exile other creatures
Kambal, Consul of Allocation ($0.61) - a 2/3 for 3 mana that makes your opponents
rethink casting spells, killing it will probably cost them 2 life and gain you 2 life
Felidar Sovereign ($0.50) - an alternative way to win plus its a decent creature on its own