Eel Juice
Be very careful when handling this stuff; Eel Juice is a sticky, rather toxic liquid that also happens to be a room temperature superconductor. The species of eel that produces the juice is also an apex predator on its home dimension / planet / elemental plane, so getting the stuff isn’t exactly easy or cheap, either. But, hey: room temperature superconductor. That’s worth a lot of money, and if it can be synthesized (Eel Juice may be esoteric, but it’s not inscrutable) then the stuff will rapidly start being worth even more.