Sale 1:

Sold for $24.49 on Marketplace.tf

https://marketplace.tf/items/51;5;u33

https://backpack.tf/item/824406475

24.49/2.07 = ~11.8

X = 12

Sale 2:

Sold for 10 keys + Strange Pro. KS Direct Hit (~3)

http://www.tf2outpost.com/trade/29250900 - B/O of 12

Seller: https://backpack.tf/profiles/76561198254703966#!/compare/1498694400/1498867200

Buyer: https://backpack.tf/profiles/76561198117586852#!/compare/1498780800/1498867200

X = 12 (Capped by B/O)

Sale 3:

Sold for 10 keys + 15 ref

http://www.tf2outpost.com/trade/29246943 - B/O of 11

Seller: https://backpack.tf/profiles/76561198261398432#!/compare/1498608000/1498780800

Buyer: https://backpack.tf/profiles/76561198254703966#!/compare/1498435200/1498694400

Keys were less than 30 ref at the time, gonna round this one up.

X = 11

Sale 4:

Quicksold for 10 keys

No outpost

Seller: https://backpack.tf/profiles/76561198127328235#!/compare/1500422400/1500508800

Buyer: https://backpack.tf/profiles/76561197977853499#!/compare/1500422400/1500508800

X = 10

Sale 5:

Sold for 10 keys

No outpost

Seller: https://backpack.tf/profiles/76561198055605614#!/compare/1497571200/1497657600

Buyer: https://backpack.tf/profiles/76561198070318593#!/compare/1497571200/1497657600

X = 10

Sale 6:

Quicksold for 10 keys + <0.5 keys in metal

No outpost

Seller: https://backpack.tf/profiles/76561198002757046#!/compare/1499126400/1499212800

Buyer: https://backpack.tf/profiles/76561198063857721#!/compare/1498953600/1499212800

X = 10

Sale 7:

Sold for 9 keys

No outpost

Seller: https://backpack.tf/profiles/76561198137335711#!/compare/1500249600/1501718400

Buyer: https://backpack.tf/profiles/76561198174759381#!/compare/1500076800/1500249600

X = 9

Sale 8:

Bulk for Green Confetti Tree?

Seller: https://backpack.tf/profiles/76561198220858440#!/compare/1500422400/1500508800

Buyer: https://backpack.tf/profiles/76561198127328235#!/compare/1500508800/1500595200

Sales at:

9

10

11

12

Buyer at 9 keys:

http://i.imgur.com/MHVJaQc.png

Excluding 9.

Sales at 10 were either quicksales or sold off the market. Excluding 10.

Going with 11-12.

7 in a row yey