The supreme crate used to exist but was removed. (Because third ownership change, so that was jacobs doing)
Removal of supreme crates were my doing, this was removed due to the items being very OP, not sure how players are still getting them, i'll look into it, thank you for reporting.
Sure, I bought mine on /ah there are a few there for sale, I paid quite a bit for it too, just so I could get one of the op tools or armor.
It might be quite nice if there was a temporary supreme crate with stuff like diamonds and emeralds, and XP and stuff, so that people who have the keys can use them up.
The keys are a collectors item. Supreme crates will not be returning for just the few users who still have keys.