Biomechan Engineer This 2/2 for two mana has a lot going on
Not only do you have a lot of good, cheap chaff cards to feed into the sacrifice engines, but many of your payoff cards dont explicitly require sacrifices at all
Generally speaking you are going to want to look for desperation sales from folks who snapped up boxes looking to crack and flip, only to find that everyone else is doing the same thing and driving prices into the ground
If your deck is built to maximize Tarmogoyf, which most Modern decks were at one point, youre already heading towards Delirium
It also features several ways to copy lands (Vesuva, Copy Land) to artificially up the town count
Winnie the Pooh - Hunny Wizard (Enchanted) Reprints are great ways to lower the cost of cards, but this Fabled version of Winnie the Pooh - Hunny Wizard is going for $220