Tinderbox

Tinderbox is a free-to-play item on the OSRS Grand Exchange in the other category.

In-game examine text: "Useful for lighting a fire."

It has a Grand Exchange buy limit of 40 every four hours, a high alchemy value of 1 gp, and item ID 590.

View on OSRS Wiki

Tinderbox shows an active flip setup with a margin of +21 gp and 5,959 trades over the last 24 hours.

At the buy limit of 40 every four hours, max profit per cycle is about 840 gp — high margin with healthy liquidity.