Eye of newt

Eye of Newt is used in Herblore to make attack potions and super attack potions. They are fairly low in price because they can be brought from Magic and Herblore stores. Eye of Newt is needed for the Witch's Potion quest and Recipe for disaster. Also, after you beat Tower of Life it can be used in the minigame, Creature Creation.

Can be bought from Betty at the magic shop in Port Sarim (it's labeled with a small fire rune on your mini map). There is a stock of 300 that sell for 3gp each. You can also get them from the herblore shop at Taverly for 3gp each.