From poppers that are readily available, I would add another GT3 150 or Cubera 150. These are the poppers I would use most often and having more than one has to be good.
But I see you do not have single pencil in there. So, I reckon that would be a good addition. See what you can find in ready stock but ones I like include Adhek Ocean Lady 160, Craftbait GT Pencil 140 and Carpenter Kattobi. Might be tough finding any of those in stock in Australia in which case try Fisherman Long Pen (but be ready for the finish to fall off), Hammerhead Tobi or one of the Full Scale pencils (can't speak for those but I am sure others can and they look great!).