Bat bones

Bat Bones is a members-only item on the OSRS Grand Exchange in the other category.

In-game examine text: "Ew it's a pile of bones."

It has a Grand Exchange buy limit of 3,000 every four hours, a high alchemy value of 1 gp, and item ID 530.

View on OSRS Wiki

Bat Bones shows an active flip setup with a margin of +231 gp and 1,495 trades over the last 24 hours.

At the buy limit of 3,000 every four hours, max profit per cycle is about 693.0k gp — high margin with healthy liquidity.