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 you can buy it from many Magic and Herblore stores.

Eye of Newt is needed for the Witches Potion quest and Recipe for disaster. Also, after you beat Tower of Life it can be used in the minigame Creature Creation.

Locations
Using the Balloon Transport System from Castle Wars to Entrana is a fast way to buy Eye of newt. It only cost 1 log and 84g for a full inventory of eyes.

If the balloon system is not yet unlocked the Port Sarim magic shop is the next closest to a bank.

Jatix's Herblore Shop in Taverley - If you have access to the Warrior's Guild, it is a short walk from that bank to the shop in Taverley and Games Necklace teleport to Burthorpe Games Room can be used for quick return.

Eye of gnome bought from the magic stall in Ape Atoll does NOT have the same effect as Eye of newt.