I think as of now the slayer shop you use Slayer points on is pretty boring and honestly theirs only a few items that are actually useful. My ideas would be maybe to add/take out some items and replace them with potions, Xp lamps, Uncut Onyx Etc, Now I'm just spit balling but I think it would be cool to make it a little better than it is.
Please Tell me your thoughts/Ideas to improve to this suggestion if you like it.