Cool deck! I'm a big fan of sacrifice decks, and Abzan is an excellent color pair for it with a sweet commander pick.
I think adding more
Blood Artist type cards would help out.
Blood Artist itself is expensive at $7, but
Zulaport Cutthroat,
Cruel Celebrant, and
Falkenrath Noble are all under $1. With things dying and recurring all the time, being able to drain the table can help keep your life total at a healthy level while chipping away at the opponents.
Midnight Reaper will draw you cards when non-tokens die, which is a very strong ability.
Teysa Karlov will double any death triggers, which can really add up with
Butcher of MalakirSince you want things in the graveyard to be able to recur, I recommend putting in more sacrifice outlets.
Viscera Seer and
Carrion Feeder are both free sac outlets, which is very important.
Ashnod's Altar might be out of budget around $6, but if you can find a cheaper copy I highly recommend getting one.
I also recommend looking at some artifact ramp. You have
Sol Ring, but the signets (in this case,
Orzhov Signet,
Golgari Signet, and
Selesnya Signet) are all excellent includes and don't cost much. You can also get the talismans (
Talisman of Resilience,
Talisman of Hierarchy, and
Talisman of Unity) but these can be a couple of dollars depending on which one you look at. At 41
lands, you could replace a few of those with artifacts and find the deck performing quite well.
I think these all would be solid inclusions and don't seem out of budget (minus a few exceptions).