I seriously don't remember what I was pricing in the first place when I started this chain of suggestions.

Sold alongside a Burning Shadows Hive Minder (~8.5, see http://backpack.tf/vote/id/53cad72f4dd7b8e73d8b4568 ) for a Disco Beat Down Headsplitter (~13.5) = ~5 for Softcap

http://www.tf2outpost.com/trade/20390136 (Next owner of Softcap offered on it earlier so Headsplitter was almost certainly offered)

http://backpack.tf/profiles/76561198082642255?time=1402988400 (Before, both Halloween hats with matching history)

http://backpack.tf/profiles/76561198082642255?time=1403074800 (After, Headsplitter with matching history and no Halloween hats)

Sold alongside a Spellbound Tippler's Tricorne (~3.7 see http://backpack.tf/vote/id/53cab8704dd7b862708b4568 ) for a Smoking Hat of Cards (~2.4 see http://backpack.tf/vote/id/53caee314dd7b835148b4568 ) and a Sulphurous Flamenco (~6.5 see http://backpack.tf/vote/id/53cae2474dd7b82e618b4568 ) = 6.5 + 2.4 - 3.7 = ~5.2

http://backpack.tf/profiles/76561197968546105?time=1402815600 (Before, Halloween items)

http://backpack.tf/profiles/76561197968546105?time=1402902000 (After, Flamenco and HoC)

Offered on (and sold for) a duped Scorching Liquidators Lid (~6.9) = ~5.7 for Softcap but sale is invalid due to duped hat and outdated price

http://www.tf2outpost.com/trade/21050578