Since Zenith is lazy ( http://backpack.tf/vote/id/55ece36edea9e9f9378b4590 ) :D , i will update this one. Thanks to Hilbert-WARing Axiom for the info on Cosa sales.

Sales

1) Quicksold for 32 keys pure. http://www.tf2outpost.com/trade/26808677

Seller: http://backpack.tf/profiles/76561198185749394?time=1439967600 (Aug 19th vs 20th)

Buyer: http://backpack.tf/profiles/76561198095335435?time=1439967600 (Aug 19th vs 20th)

As you see there are differences between backpacks. I contacted the buyer (Hilbert-WARing Axiom) and confirmed that he paid 32 keys pure for it:

http://imgur.com/ck8VaNK

_______________________________________________________________

2) Quicksold for... 36 keys? --- http://www.tf2outpost.com/trade/26978620

http://backpack.tf/profiles/76561198051856084?time=1441609200 (Sept 7th vs 9th)

_______________________________________________________________

3) (Y) Sold for a Flaming Lantern Cosa Nostra Cap (X) http://www.tf2outpost.com/trade/26850688

http://backpack.tf/profiles/76561198095335435?time=1440399600 (Aug 24th vs 25th)

Minis on the Cosa ------- I will later update this one properly

- Sold for a Cloudy Moon Heavy Duty Rag (45.5 keys)

http://backpack.tf/profiles/76561198046429263?time=1440054000 (Aug 20th vs 21st)

I have no idea who offered what, as this trade closed 3 weeks before the sale: http://www.tf2outpost.com/trade/26646663

Doing maths: X= 45.5*0.9= ~41 keys

------------------------------------------------------

- Hilbert sold his Cosa for a Stormy 13th Hour Détective Noir (53 keys) + 10 keys ----- Capped at 50 keys

http://backpack.tf/profiles/76561198095335435?time=1441695600 (Sep 8th vs 9th)

http://www.tf2outpost.com/trade/26965890

Taking mid range on minis 41-50 keys ---- ~46 keys

Back at the main sale: Y= ~46 keys

_______________________________________________________________

4) Sold for a Misty Skull L'Inspecteur (~45 keys)

http://backpack.tf/profiles/76561198051856084?time=1441522800 (Sept 6th vs 7th)

Shanter was offered http://www.tf2outpost.com/trade/26974738

_______________________________________________________________

Couldn't find the third Shanter, the other one is this: http://backpack.tf/item/3543716221

- Quicksales at 32 and ~36. Sales at 45 and 46. So what range will i take...?

Yeah, you guessed right, i will take 45-46 keys range ... What, you didn't guess it? Shame on you.

Criticism appreciated!

I found the other Shanter, and it has one more sale:

(X) Sold with a Burning Flames Tam O' Shanter (51 keys) for a Searing Plasma Ol' Geezer (15 keys) + 65 keys

http://backpack.tf/profiles/76561198021183702?time=1441350000 (Sept. 4th vs 5th)

X=65+(15-51)*0.9= ~33 keys

Since i have two quicksales for 36 (?) and 32, then i would say it's an outlier as well.

Also, i updated the F.L. Cosa after this one, but it got approved first. I didn't apply double overpay on it, that's why i used 46 keys. Not sure if it was needed.