Hey there, I can provide some more info on a few of these sales :)

Sale 1

I bought it for 18 keys through my buy order - https://i.imgur.com/GZrBlFL.png

Sale 3

Equilibrium bot is my bot and it was actually an item overpay offer I received rather than a purchase with keys. Gladiator just records it at the buy price at the time of the trade. This sale would be invalid anyway - https://i.imgur.com/mBhdPNU.png

Sale 4

Ignore this. After buying it for 18 keys (sale 1), I deposited it in my bot and then withdrew it to deposit onto marketplace, which sold the next day (the 25 key mp.tf sale).

Additional sale

I also sold one over 2 weeks ago for 23 keys 26 ref, which supports the bottom range - https://i.imgur.com/9eOptYV.png

Hope this helps!

On a side note, if you ever come across a trade involving me or my bots, more than happy to share/clarify the details (feel free to add me) :D