I was going to say this was the worst of all the 'das ___' hats in TF2 but then i remembered das maddendoktor exists.

Sold for a Circling TF Logo Tippler's Tricorne(~15 Keys) and ~24 Keys in Sweets(B/O was 30)

http://backpack.tf/profiles/76561198108148076#!/compare/1481500800/1481587200

http://backpack.tf/profiles/76561198066950212#!/compare/1481587200/1481673600

http://www.tf2outpost.com/trade/28654220

Sold for a Blizzardy Storm Prince Tavish's Crown(16.5 Keys), an Australium Ambassador(~13.5 Keys at the time) and ~4 Keys in Sweets(34 Keys total)(B/O was 32)

http://backpack.tf/profiles/76561198055224435#!/compare/1480636800/1480723200

Sold for a Blizzardy Storm Crocleather Slouch(13.5 Keys) and ~18.5 Keys in Sweets(32 Keys total)

http://backpack.tf/profiles/76561198096389539#!/compare/1483056000/1483228800

Sold for 29 Keys

http://backpack.tf/profiles/76561198121731353#!/compare/1485993600/1486080000

29-32.

Credits to Mindacos for the suggestion. He found the proof, I'm just posting it.