The Happy Horn is the only Sparrow Horn that will be available to re-acquire through the Sparrow Collection. Legendary quality Sparrow Horns are still available to be purchased from Eververse Trading Co. after the Sparrow Racing League event ends. Please note: Rare quality Sparrow Horns could only be earned during the Sparrow Racing League event and became unusable after the event ended, but were not be removed from player Inventories. They will appear grayed out in the player's Inventory and can be discarded. https://www.bungie.net/en/Forum/Post/178797767/0/0