my first suggestion that relies on another currently in-progress suggestion. and now i can go to bed.

sold + peace dead cone for killawatt bonk helm

http://www.tf2outpost.com/trade/18763871

2.2 - 0.9 = ~1.3

dead cone update here: http://backpack.tf/vote/id/533cb06c4cd7b8f5468b462d

my sales (yeah, i've bought and sold twice):

bought for 1 bud 1 key, quicksale.

sold for o fire modest ~2.7

http://www.tf2outpost.com/item/440,2450956065,139,5 - modest

http://www.tf2outpost.com/item/440,2452954700,627,5 - menco

bought back from the same guy for a disco bicorne (unpriced, also the bicorne later got duped by steam support), he added a p.e. festiviser, 1 bud and sweets. ~???

http://www.tf2outpost.com/item/440,2446818206,607,5 - bicorne

http://www.tf2outpost.com/item/440,2452954700,627,5 - menco

http://www.tf2outpost.com/item/440,2452954598,338,5 - festiviser

i offered on and got a duped searing pyromancer's; ~1.8

http://www.tf2outpost.com/item/440,2485142364,316,5 - mancer's

http://www.tf2outpost.com/item/440,2452954700,627,5 - menco

it may be duped, but it should still be 1.8 based on what the previous owner paid, and therefore valued it at.

http://imgur.com/6qSXWKj - screenshot of hexahe telling me what he paid (1 bud 16 keys.)

2.7 looks like a big outlier, buyouts have come down from 3 when I sold it then, to 2 now.

As always, vote based on proof presented, present counterproof if you've got it, and let me know if I can improve this suggestion. Thanks for reading.