[b]Green Confetti Détective Noir (20-24 keys)]/b]

Price is 4 months old.

http://www.tf2outpost.com/trade/8335994

sold for 1 bud, b/o was 24 keys (quickbuy)

http://www.tf2outpost.com/trade/9034090

b/o 20 keys, sold (maybe for b/o)

http://www.tf2outpost.com/trade/9036140

sold for white bills (9.5) + after eight dashin (3 keys) + greande launcher with two parts (4.5 keys) + vintage football helm (1 key) + meet the medic (1 ref) = ~18 keys pure

http://backpack.tf/id/76561198065384922?time=1362297600 --> http://backpack.tf/id/76561198065384922?time=1362643200

http://www.tf2outpost.com/trade/7022444

sold for 1 bud (b/o) --> needed his hat for a fetti set (overpaid?)

http://www.tf2outpost.com/trade/7517724

c/o 20 keys (no proof)

http://www.tf2outpost.com/trade/7734514

next owner --> nothing below 20 keys, so I asume he bought it for 20 keys (c/o on previous owners trade). Got added, buyer paid most probably more than 20 keys.

http://www.tf2outpost.com/trade/7888726 --> http://www.tf2outpost.com/trade/7931275

sold for 1 bud? maybe he added sweets to the noir.

http://www.tf2outpost.com/trade/7961376 --> http://www.tf2outpost.com/trade/8066127

sold for 1 bud? maybe he added sweets to the noir.

http://www.tf2outpost.com/trade/8072243

sold for 20 keys, sold (maybe for b/o)

Conclusion: We have 1 sale at 18 keys and 2 sales at 1 bud that are proven. Both of those proven 1 bud sales overpaid for stated reasons. Some 20 key buyouts in the history of these hat. Because that range would be too wide I suggest a mid value for it.