Nice one, never had anything that good yet even though I'm doing 4 chests almost daily. Bottom robe of subjugation has been the best one I got, it was around 5 mil for cash out if I remember right.
Best thing I got was a lucky armadyl godsword, which I lost when I thought it would be kept if I protected item with it in the wilderness. Learned that it wouldn't be saved a little too late.
Damn thats nice, when I do the squeal I normally get like 1 star of xp and one random junk thing worth 10k, the star is worth it though as I hate training