Purple dye

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

In-game examine text: "A little bottle of purple dye."

It has a Grand Exchange buy limit of 150 every four hours, a high alchemy value of 3 gp, and item ID 1773.

View on OSRS Wiki

Purple Dye shows an active flip setup with a margin of +555 gp and 1,593 trades over the last 24 hours.

At the buy limit of 150 every four hours, max profit per cycle is about 83.3k gp — high margin with healthy liquidity.