Cares' Random Unusual generator! I landed on this Beauty.

Sale 1

http://www.tf2outpost.com/trade/23244486 Sold for Beams Pickehaube

Stahlhelm History http://backpack.tf/item/1193262881

Pickehaube History http://backpack.tf/item/157097767

3.8 = X * 0.9

X = 4.2

Pickehaube mini

MiniSale 1

http://www.tf2outpost.com/trade/23129074 Sold with G. Fetti Veil + Australium Medi-Gun + Australium Flame Thrower for Cloudy Moon Demo's Fro

Medi-gun History http://backpack.tf/item/2915440757

Veil History http://backpack.tf/item/401865225

Flame Thrower History http://backpack.tf/item/2270697356

Demo Fro History http://backpack.tf/item/1239695051

11 + X + 1.3 + 1.9 = 18

14.2 + X = 18

X (Pickehaube) = 3.8

MiniSale 2

http://www.tf2outpost.com/trade/22544759 Sold for DBD Head Warmer

Head Warmer History http://backpack.tf/item/2326542146

Pickehaube History http://backpack.tf/item/157097767

HW wasn't outdated at the time

HW = 3.8

Pick = 3.4

Sale 2

[OUTLIER]

Sale 3

http://www.tf2outpost.com/trade/22616200 Sold for Stormy Muffs

Muffs history http://backpack.tf/item/1712227340

Stahlhelm History http://backpack.tf/item/1193262881

4.15 * 0.9 = 3.735, rounding to 3.7

Sale 4

http://www.tf2outpost.com/trade/23056037 Sold for 4 buds pure

http://backpack.tf/profiles/76561198048754056?time=1413097200 Backpack after Sale

Second Sale seems like an Outlier.

I hope I did good ^~^