Buy OSRS Red dye
Red dye is a useful item in Old School RuneScape. It is made by taking 3 redberries and 5 coins to Aggie in Draynor Village. Ali the dyer in Pollnivneach can also make it for 25 coins. You can buy it from Oronwen in Lletya for 6 coins as well.
Red dye has many uses. You can mix it with yellow dye to make orange dye, or with blue dye to make purple dye. You can also use it to dye a normal cape red.
Many quests need red dye. It is used in Goblin Diplomacy, Enlightened Journey, Getting Ahead, Mourning's End Part I, and Song of the Elves. You may also need 1 to 3 red dyes for Ghosts Ahoy, since the color needed in that quest is random.
Red dye is tradeable and noteable, so it is easy to move around. It is not stackable and cannot be equipped. It weighs only 0.02 kg. Keeping a few in your bank saves time when a quest calls for one.