You can never throw more than one lure at a time, regardless of how many you own. The lure will return to the player's inventory if it is not retrieved within certain amount of time after being thrown. This prevents players from leaving without their lure. You can buy one from Yaktwee Swinmari Cianta for 2,000 coins, who can be found south-west of the Tree Gnome Stronghold. A player must have 72 hunter to open the shop and buy the item.