I have the Collector's Helmet Without a Home Chemistry Set btw...

Sale 1

http://www.tf2outpost.com/trade/24045094 Sold for C9 Oiled Baker Boy

HWAH had no trade, presuming offered

X = 1.1

Baker http://backpack.tf/item/2851724873

HWAH http://backpack.tf/item/3197824458

Mini for Oiled

[No OP Trade] Sold for 16 keys pure

X = 1.1

Keys http://backpack.tf/profiles/76561198138442494?time=1420197231#page0

Baker http://backpack.tf/item/2851724873

Sale 2

http://www.tf2outpost.com/trade/24095849 Sold for Steaming Beanie

B/O for Beanie was 15 keys (1.2)

B/O for HWAH was 19 keys (1.4~)

X = 15*0.9

X = 14 keys (1.1)

Beanie http://backpack.tf/item/703741543

HWAH http://backpack.tf/item/3197824458

Mini for Beanie

One with a B/O for 15 keys in Classifieds, using 15 keys

Sale 3

http://www.tf2outpost.com/trade/24057364 Sold for DBD Ketche

HWAH had a B/O of 1.5

Ketche had a B/O of 1.3

X = 1.1*0.9

X = 1

Ketche http://backpack.tf/item/2661523252

HWAH http://backpack.tf/item/3197824458

Ketche wasn't outdated at time of sale