Good hat with a slightly less not good effect.

Sold for a Purple Energy Carouser's Capotain(25 Keys)

http://backpack.tf/profiles/76561198364424477#!/compare/1495843200/1495929600

Sold for an Australium Wrench(19 Keys) and 4 Keys(23 Keys total)

http://backpack.tf/profiles/76561198093765664#!/compare/1489017600/1489104000

Sold for an Orbiting Planets El Jefe(17 Keys), a Dead Presidents Bombing Run(11.5 Keys, round to 12) and ~1 Key in Sweets(30 Keys total, Outlier)

http://backpack.tf/profiles/76561198050062763#!/compare/1491091200/1491177600

23-25.

Credits to Mindacos for finding the proof. All I did was make the actual suggestion.