Sale 1:

Sold for 9 keys

Seller: https://backpack.tf/profiles/76561198002757046#!/compare/1515628800/1515715200

Buyer: https://backpack.tf/profiles/76561198262779853#!/compare/1515542400/1515715200

X = 9

Sale 2:

Sold for 7 keys + 19 ref

Seller: https://backpack.tf/profiles/76561198075119827#!/compare/1516838400/1516924800

Buyer: https://backpack.tf/profiles/76561198085482367#!/compare/1516838400/1516924800

X = 8

Sale 3:

Sold for 8 keys and some ref to a quickbuyer

Seller: https://backpack.tf/profiles/76561198181925323#!/compare/1515456000/1515628800

Buyer: https://backpack.tf/profiles/76561198002757046#!/compare/1515542400/1515628800

X = 8

Sale 4:

Sold for 7 keys + 24 ref to a quickbuyer

Seller: https://backpack.tf/profiles/76561198202921439#!/compare/1516320000/1516406400

Buyer: https://backpack.tf/profiles/76561198048851745#!/compare/1516320000/1516406400

X = 7

Sale 5:

Sold for 7 keys

Seller: https://backpack.tf/profiles/76561198143912133#!/compare/1516406400/1516492800

Buyer: https://backpack.tf/profiles/76561198371517053#!/compare/1516406400/1516492800

X = 7

Sale 6:

Sold for 2 taunt kill parts (~5) + 2 keys and some ref

Seller: https://backpack.tf/profiles/76561198345528421#!/compare/1515110400/1515196800

Buyer: https://backpack.tf/profiles/76561198271801065#!/compare/1514937600/1515196800

X = 7

Sale 7:

Sold for 7 keys

Seller: https://backpack.tf/profiles/76561198355520251#!/compare/1516665600/1516752000

Buyer: https://backpack.tf/profiles/76561198160856661#!/compare/1516665600/1516752000

X = 7

Sale 8:

Sold for a bunch of items

Seller: https://backpack.tf/profiles/76561198342161127#!/compare/1516752000/1516838400

Buyer: https://backpack.tf/profiles/76561198115599217#!/compare/1516752000/1516838400

probably close to 7 or 8

Sale 9:

Bulk for Kill-a-Watt Crocleather Slouch

Seller: https://backpack.tf/profiles/76561198084500613#!/compare/1514764800/1514851200

Buyer: https://backpack.tf/profiles/76561198132291667#!/compare/1514764800/1514851200

Sellers:

~7.5 keys:

https://i.imgur.com/Bnjvuny.png - 2 days

https://backpack.tf/item/5843269998

9 keys:

https://i.imgur.com/7GYFvjP.png

https://backpack.tf/item/3742747331

~11.4 keys:

https://i.imgur.com/tp9Xblv.png - 18 days

https://backpack.tf/item/3289267024

Sales at:

7 (4x)

8 (2x)

9

7-9.