After spending hours waiting for the black full helmet and black platelegs to respawn in the champions guild store, I gave up on buying black platelegs from the store (having just bought the helmet) and looked to see what monsters dropped the platelegs I sought. The only creature on the list was animated black armor.
Great, I need to kill my own armor to get some. Very thoughtful, Jagex, you just stopped everyone on Runescape from doing your newest quest.
But then, I remembered a small shop in Al Kharid. Running to the desert that I had been in earlier that day, trying to find granite, I went to the shop and bought the platelegs.
I took the gnome glider to White Wolf Mountain and hurried to falador, then Ice Mountain, then finally to the Black Knights’ Fortress. I donned my brand new bronze medium helmet and iron chainmail body and rushed through the doors of the fortress so nobody would recognize me. I hid in a corner and changed into my hard-to-get black armor and then headed down the ladder.
I saw King Arthur and freed him from the stone enchantment. As I was leaving, someone yelled my name and I ran back. They begged me to buy my armor, and since I no longer needed it, I sold it to them for their price of 40000 coins. I now have 125000+ coins in my bank account.
I ended my day in Camelot and dueled a few of the knights in a safe arena that was enchanted by Merlin.