Playing around with mono-white lifegain in pioneer while keeping on a relative budget. Making do without useful pieces like the Soul Sisters (Soul Warden and Soul's Attendant) and token support like Lingering Souls, Spectral Procession, Battle Screech, etc. That said, I think I've made some fair compromises with what I could find. We still have Ajani's Welcome to act as a substitute for a set of one of the Soul Sisters. To slow down our opponent's creatures as well as gain life whenever they come out, we also have Authority of the Consuls.
Aside from those and plenty of other decent lifegain tools, we have our powerhouses in the form of Ajani's Pridemate and Archangel of Thune to capitalize on that lifegain, as well as Oketra's Monument to help reduce casting costs as well as generate more bodies. I had Felidar Sovereign as a wincon, but it seemed too slow to bring out for the type of aggro we want, so I'm swapping out Linden, the Steadfast Queen to test her out. For protection, we have Brave the Elements, which will grant all of our creatures protection from the color of our choice until the turn ends. We also have Banishing Light as removal, as well as a one-sided wipe/protection in the form of Settle the Wreckage.
Finally, we have Ajani, Strength of the Pride himself. Ajani does a lot for us, as he rewards us for getting lots of creatures out with more life, can make even more Pridemates to oppress our opponent, and has good odds of being an instant one-sided wipe if you get him out with enough life, getting rid of all your opponent's pesky creatures and artifacts for the simple price of exiling Ajani.
As for the sideboard, it's tricky without knowing what the format environment is going to look like. Even so, I think it's a safe bet to include some graveyard hate, as well as things to slow down spells-matter decks and the like. Enchantment/artifact removal is always good to have access to, and even without the fetch lands to worry about, keeping your opponents from searching their decks with things like Attune to Aether and such with Aven Mindcensor seems prudent too.
Anyway, I'm still not super familiar with how these metas worked in their time, but I'll continue researching and improving this as I go. Feel free to offer suggestions!
THB Update:
With the recent spoilers of Heliod, Sun-Crowned I am certainly considering slotting a couple copies in. Will need to decide what the best cards to cut for him will be. I'd also consider tracking down and slotting in some Walking Ballistas, but they're not exactly budget-friendly and given the uproar with Oko recently I wouldn't be surprised if the Heliod+Walker combo gets banned pretty quickly once it hits the format. As of right now, between prerelease and the actual release of THB, Heliod is ranging in the $20-25 zone per copy, so we'll see how it looks after the market has normalized. I'd like to keep the decklist close to $150 but may change this to under $200 if Heliod remains at that price point. The newly spoiled Shadowspear is definitely something I may want to test out. Lifelink, Trample, a +1/+1 buff, and the ability to eliminate Hexproof/Indestructible from your opponents' things is incredibly useful, and could make all the difference in making this deck even more aggressive. Slap one of these bad boys on a Pridemate and I doubt you'll be sorry, though whoever is at the receiving end might end up that way.