Hmm... Interesting...

Sales:

http://www.tf2outpost.com/trade/20636610 Added Stormy Chapeau (Outdated at 1.7, mini at 1.55) for Harvest Fuka (6.2)

(6.2 * 0.9) - 1.55 = 4.03 (rounding to 4)

Histories:

http://www.tf2outpost.com/item/440,2757885318,337,5

http://www.tf2outpost.com/item/440,2709902299,397,5

http://www.tf2outpost.com/item/440,2757885360,395,5

http://www.tf2outpost.com/trade/19162987 Sold for stormy Phantom (2.3) + O.Fire Cosa (Outdated at 1.2, mini at 1.1)

3.4 * 0.9 = 3.06 (rounding to 3.1 just to be different and awkward >:3)

Histories:

http://www.tf2outpost.com/item/440,2787328272,337,5

http://www.tf2outpost.com/item/440,2528002685,337,5

http://www.tf2outpost.com/item/440,2528002696,459,5

Chapeau mini:

http://www.tf2outpost.com/trade/19772762 Sold + sweets (~0.2) for KaW Noir (~2)

(2 * 0.9) - 0.2 = 1.6

Histories:

http://www.tf2outpost.com/item/440,2671686153,397,5

http://www.tf2outpost.com/item/440,2602780983,319,5

http://www.tf2outpost.com/trade/20057091 Sold for Planets Runner (1.4) + sweets (~0.3)

1.7 * 0.9 = 1.53 (rounding to 1.5)

Histories:

http://www.tf2outpost.com/item/440,2704428059,397,5

http://www.tf2outpost.com/item/440,2634535875,760,5

1.5 - 1.6 on the Chapeau.

Cosa Mini:

http://www.tf2outpost.com/trade/20349460 Sold for 18 keys (Buds were @ ~16.5, = 1.1)

http://www.tf2outpost.com/trade/20348505 Sold for 1 bud + Festive Medigun (~1.1)

Using 1.1.

Let it ride.