This should be quite easy with some sacrifice fetch lands and you get a good-sized creature for its mana value
Emperor of Bones (MH3-453) - Modern Horizons 3: (Extended Art) Emperor of Bones (MH3-453) - Modern Horizons 3: (Extended Art) Wizards of the Coast This item is like new, pulled from a sealed pack
2 Blood Moon Many decks in Modern will be concerned when this hits the battlefield, and that includes Affinity
Radiants contribute the second-largest EV component
In the similar vein there are two 3 cost creatures that only get two mana, but also don't need to tap, so you get access as soon as you recur them: Blood Vassal and Basal Sliver
That said, you can pack your deck with Hyena Umbra, Spirit Mantle and Aura-based removal like Darksteel Mutation, Chains of Custody and Ossification to get your card draw up for Sram