Cheap Crystron

The entire main deck is ~$25 on TCGPlayer (Mar 2025), and 13/18 of the non-engine assume you bought the Blue-Eyes White Destiny structure deck x3. Otherwise, just toss in your old shredded copies of Dark Hole or whatever until you hit 40 cards.

This is 95% full power because the one card that's missing is 3x Forbidden Droplet, which alone would double the cost of this deck.

EDIT Feb 2025: Swapped the Terrortop engine (3x Speedroid Terrortop, 1x Speedroid Taketomborg, 1x Cherubini, Ebon Angel of the Burning Abyss) for 2x Tidal, Dragon Ruler of Waterfalls, added Vermillion Dragon Mech. Both are valid, but Tidal frees up a bit of space for either non-engine or Rosenix + Praisortle utility.

EDIT Mar 2025: Thanks to OTS Pack 27, Citree suddenly went from sorta expensive to a pile common, Sulfefnir's now also a pile common, and Maze of the Master reprinted Quariongandrax so he's cheap too. So, uhhh, wow this deck is now insanely cheap - a couple months ago this started at ~$80 and now the Main + Extra is sub-$50. Which basically makes this an unofficial structure deck.