Sale :

Sold for Steaming Broadband Bonnet (12)

No outpost

Seller: http://backpack.tf/profiles/76561198056030479#!/compare/1476748800/1476835200

Buyer: http://backpack.tf/profiles/76561198253681121#!/compare/1476403200/1476835200

X = 12

Sale :

Sold for Peace Sign Mongolian (Mini at 10 below) + minor item

http://www.tf2outpost.com/trade/28563447 - B/O of 10

Seller: http://backpack.tf/profiles/76561197961492044#!/compare/1477353600/1477440000

Buyer: http://backpack.tf/profiles/76561198207609629#!/compare/1477353600/1477440000

X = 10

Sale : (Dupe)

Sold for Blizzardy Dread Knot + ~0.5 keys in metal/items

http://www.tf2outpost.com/trade/28573017 - B/O of 10

Seller: http://backpack.tf/profiles/76561198058691397#!/compare/1477958400/1478131200

Buyer: http://backpack.tf/profiles/76561198162192537#!/compare/1477872000/1478044800

Should at least be 10 keys, or even cap at the B/O

X = 10

Sale : (Dupe)

Sold for 10 keys?

No outpost

Seller: http://backpack.tf/profiles/76561198107041561#!/compare/1475625600/1476057600

Buyer: http://backpack.tf/profiles/76561198159517089#!/compare/1474588800/1475884800

X = 10

Sale :

Sold for 9 keys

No outpost

Seller: http://backpack.tf/profiles/76561198287835588#!/compare/1477267200/1477353600

Buyer: http://backpack.tf/profiles/76561197961492044#!/compare/1477267200/1477353600

X = 9

Sale :

Sold with a key in sniper skins for Spec. KS Aussie Frontier Justice (9)

No outpost

Seller: http://backpack.tf/profiles/76561198165718588#!/compare/1477526400/1477612800

Buyer: http://backpack.tf/profiles/76561198096581757#!/compare/1477526400/1477612800

X = 8

Sale :

Bulk for Dead Presidents Head Warmer

Seller: http://backpack.tf/profiles/76561198137505619#!/compare/1476316800/1476403200

Buyer: http://backpack.tf/profiles/76561198138844587#!/compare/1476316800/1476403200

Should be used to update the Head Warmer

Sale :

Bulk for Smoking Brainiac Hairpiece

Seller: http://backpack.tf/profiles/76561198138844587#!/compare/1476576000/1476662400

Buyer: http://backpack.tf/profiles/76561198056030479#!/compare/1476576000/1476662400

Should be used to update the Head Warmer

Peace Sign Mongolian Mini:

Sold for Spec. KS Aussie SMG (7) + 3 keys

http://www.tf2outpost.com/trade/28542210 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198019556015#!/compare/1476489600/1476576000

Buyer: http://backpack.tf/profiles/76561198208815717#!/compare/1473724800/1476576000

X = 10

Sellers:

11 keys:

http://i.imgur.com/4dfekD3.png - 15 days

http://backpack.tf/u/76561198076020691

http://www.tf2outpost.com/trade/28648371

Buyer at 9 keys:

http://www.tf2outpost.com/trade/23966370

Sales at:

8

9

10

12

Buyer at 9 keys shows that 9 and below are too low. Excluding 9 and 8.

Given the abundance of sales for lower, the seller at 11 for 15 days, and the sellers for slightly less on the steaming bonnet, going to exclude 12.

Going with 10 flat