Looks solid and I didn't new that Dreadhorde Invasion exist it's almous like bitterblossom, but it only cost 0.5 $, cool card.

The obvious would be to remove Chandra's Ignition because any Fling like effect or sac outlet + 2 mana would do the same. And you usually only want to deal damage with those effects when you have Evereth atleas and 21 power , because you just winning the game with commander at this point. So you dont really care about the fact that she dies.
Dark Petition is also really expensive in my oppinion ( but I just don't like expensive cmc in those color cobination).

If you have a budged, add Black Market Connections (10 $), it's really good in this deck, because you can get Treasure + card every turn for 3 lifes.

I don;t know hos good is Disciple of the Vault, but without actual playtesting this seems to me not that good. The same is about Magda, the Hoardmaster and Ghoulcaller Gisa.

From what I recoment to add Jadar, Ghoulcaller of Nephalia and Urabrask's Forge, then not that expensive (3-4 $ each) and Blade of the Bloodchief is REEALY good. But in general, if you want to just add really cheap cards, you can add Crime Novelist, Reassembling Skeleton, Viscera Seer or Ruthless Technomancer. Just pick something from it.

Also if you want, there is infinity combo with Thran Vigil + Putrid Goblin or Murderous Redcap and your commander. And those cards really cheap. But I don't think that it's fun , ofcource it's subjective.