Spike Feeder + Archangel of Thune

After the release of Magic 2014 and Archangel of Thune, many Melira Pod decks started including the 2-card combo with Spike Feeder, giving them another way to gain an infinite amount of life and put an unlimited number of +1/+1 counters on all of their creatures. I chose for this to be the only combo in Bant Pod for a number of reasons. For one, we don't have to play awkward creatures to combo out. Viscera Seer, Melira, Sylvok Outcast, and Cartel Aristocrat aren't the greatest of creatures to be trying to attack your opponent to death with. Spike Feeder and Archangel of Thune on the other hand help by being able to gain you life and make your dudes larger when needed. They also happen to interact well with the Persist creatures Kitchen Finks and Glen Elendra Archmage. I also chose to only include this combo because of its relative ease to set up. A two-card combo is much easier to assemble than any possible three-card combo, even with a Birthing Pod in play. You have to actively figure out new ways to assemble all of your pieces in Melira Pod which can sometimes leave you in awkward board states for a turn, whereas in this deck you can get everything out in one turn and be ready to go infinite.
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Adding more combo pieces to the shell is a reasonable answer if the deck isn't running chord of calling. People are just going to bolt Fauna Shaman - it's too slow, and it's just going to waste your turns.

I suppose you could use Congregation at Dawn (instant, but have to wait a turn. Not a bad option), Jarad's Orders (get it in your hand, but definitely slow), a flipped Garruk Relentless (even slower), Ranger of Eos (only gets the sac outlet though, so meh), or Summoner's Pact.

Summoner's Pact is still a $7 card, so not exactly budget. It's only green creatures though, like Green Sun's Zenith. It's super risky to play if they have a Tectonic Edge in play and/or they bolt your mana dork - it will force you to combo a turn or two later. If you can win the turn you play it, it can be a super good card though.

Congregation at Dawn gives you card disadvantage and it also has tempo loss, but you can assemble the combo very quickly with this card since it's a 3-mana tutor. Hell, you can get the entire combo if you don't have a single piece of it as it has no colour restriction. This card also has the advantage of being extremely cheap to obtain. Probably the best choice for budget, next to Jarod's Orders.

Jarad's Orders is another good budget option. It basically does what Summoner's Pact does (but isn't colour-restricted), however it'll cost mana on your turn, which makes you an entire turn slower. One upside to this is that the discarded creature works with Eternal Witness and Reveillark though, and you won't risk losing the game if your combo is disrupted or they bolted a mana dork and you can't pay the upkeep costs on Summoner's Pact. It'll do the job at least. It is nowhere near as good as Chord of Calling, but what is?

I think some testing would be required to see which of these 3 best candidates work best in the deck. You could also get 3 of each of the cheaper tutors and play test with them. If they both suck, then just get Chord of Calling and stop complaining Smile

If one of these options actually functions okay, I guess I'd cut 2 or 3 of the following cards: Harmonic Sliver, Sin Collector, Thalia and one of the mana dorks. Thalia is probably the first to go to the sideboard, as it makes your tutoring much worse. Next would be Harmonic Sliver. I am not experienced enough to know if cutting the Sin Collector is better than cutting the mana dork - my gut says the mana dork - but I don't see where else to cut beyond these.

As I said before, try Glittering Wish.