[[Judge's Familiar]] seems like the most significant of these. It looks like the closest blue has to that ability right now is [[Spiketail Hatchling]], and the closest white has is [[Soulsworn Jury]].
I wouldn't be shocked if [[Boros Elite]] or [[Slitherhead]] showed up in some decks. Those seem very cost-efficient.
[[Sprouting Renewal]] is potentially free, but the Sorcery speed probably dooms it.