Both Heckel Funch and Hudo in the Grand Tree sell 10 oranges for 70 coins each, but this is very time consuming due to the slow shop respawn of oranges. Obtaining Oranges from the barman is slow, but much cheaper at 20 coins each.
It can also be picked from an Orange tree grown using the Farming skill at level 39. Players get 13.5 experience points every time they pick an orange from the tree. When the tree is full with oranges the player can pick 6 oranges for a total of 78 experience. More oranges grow on the tree with time.
Players with 69 Summoning can summon a Fruit Bat which can produce oranges with its Fruitfall special move. They can also go to Karamja and choose the "Fly" option to have the familiar forage oranges.