Well this hat is still 1 of 1 in TF2 and though I can understand why it hasn't been suggested until now

I have some evidence for the trade in TF2 outpost with the items history to support it

First:

G.E Gym Rat for Electrostatic Pirate Bandana [Gym Rat is ~27 Keys]

Original Owner trade http://www.tf2outpost.com/trade/28107454

Proof from item history of both gym rat and bandana :

http://imgur.com/uEYUpmv

http://imgur.com/bzYZAjb

Second:

Vivid Plasma Swagman's Swatter for Electrostatic Pirate Bandana [Swatter is ~35 Keys]

Owner Trade with the offer http://www.tf2outpost.com/trade/28200014

History Proof:

http://imgur.com/DsNLr7I

http://imgur.com/ahzZb6J

I suggest 31 keys as a price which is the average of 27 and 35