Transmute Artifact

Sacrifice an artifact. If you do, search your library
for an artifact card. If that card's converted mana
cost is less than or equal to the sacrificed
artifact's converted mana cost, put it onto the battlefield. If it's greater, you may pay {x}, where
X is the difference. If you do, put it onto the battlefield. If you don't, put it into its owner's graveyard. Then shuffle your library.