Rune essence

Rune Essence is a free-to-play item on the OSRS Grand Exchange in the runes category.

In-game examine text: "An unimbued rune."

It has a Grand Exchange buy limit of 20,000 every four hours, a high alchemy value of 2 gp, and item ID 1436.

View on OSRS Wiki

Rune Essence shows an active flip setup with a margin of +2 gp and 503,701 trades over the last 24 hours.

At the buy limit of 20,000 every four hours, max profit per cycle is about 40.0k gp — high margin with healthy liquidity.