Sigil of the Serpent

High alchemy turns Sigil of the Serpent into 12,000 gp. Buying one at 100,000 gp (its guide price, as it has not traded today) and casting with a nature rune at 137 gp costs 100,137 gp. That is a loss of 88,137 gp per cast at its guide price, so it is not worth alching for profit right now.