You won't sacrifice a creature
First, we do need better and more effective reprints to bring prices down and should do everything we can to push Wizards in this direction
For example, if you control an Ajani's Pridemate ("Whenever you gain life, put a +1/+1 counter on Ajani's Pridemate") and you activate Wayta, Trainer Prodigy's second ability targeting a creature you control with lifelink and another creature you control, the triggered ability of Ajani's Pridemate will still trigger only once
If youre interested in getting yourself a set of these very special cards, you have until the end of August to pre-order them
As it turns out, the Midnight Guard will untap as soon as that Elf enters the battlefield, ready to tap to produce more Elves ad nauseam
Then search your library for a basic land card, put it onto the battlefield tapped, then shuffle