Crystal of power (flatpack)

High alchemy turns Crystal of power (flatpack) into 6 gp. Buying one at 6,368 gp (its guide price, as it has not traded today) and casting with a nature rune at 138 gp costs 6,506 gp. That is a loss of 6,500 gp per cast at its guide price, so it is not worth alching for profit right now.