Argueably the most ignored hat barring the Katyusha and Cyborg Stunt Helm.

Sold for a Terror-Watt Fed-Fightin' Fedora(2.8 with Overpay)

http://www.tf2outpost.com/item/440,2800972572,30406,5 Peacenick's History

http://www.tf2outpost.com/item/440,2803111378,780,5 Fedora History

Sold for a Kill-a-Watt Coupe D'Isaster(0.9 with Overpay)( backpack.tf/vote/id/53f18f2760dcd5e31a8b45da ) and a Circling TF Logo Stout Shako(1 with Overpay)(1.9 Total)

http://www.tf2outpost.com/item/440,2803111399,30406,5 Peacenick's History

http://www.tf2outpost.com/item/440,2804379541,330,5 Coupe History

http://www.tf2outpost.com/item/440,2804379531,251,5 Shako History

Two sales, 1.9-2.8 should do for now.

Additional Proof/Counter-Proof/Constructive Criticism/Feedback is always appreciated.