Where do you buy "Broad Bolt Heads" or "Unfinished broad bolts" in runescape?

I was watching a youtube vid on the fastest way to 99 fletch and i went to a slayer mast to buy and he didnt hav them in stock. Does anyone know why he showed it in the video: http://www.youtube.C 0 M/watch?v=0oNkXPkZfUE. Why is it in the video but not in the game. Thanks. You can check for urself if u want. Add me. Rs username: xBxPx