Sale 1:

Sold for 40 keys

Seller: https://backpack.tf/profiles/76561198068844434#!/compare/1535673600/1535846400

Buyer: https://backpack.tf/profiles/76561198070244428#!/compare/1535760000/1535846400

https://backpack.tf/item/5249701429

X = 40

Sale 2:

Sold for 37 keys

Seller: https://backpack.tf/profiles/76561198047941585#!/compare/1532649600/1532736000

Buyer: https://backpack.tf/profiles/76561198056531196#!/compare/1532649600/1532736000

https://backpack.tf/item/5249701429

X = 37

Other Sales:

https://backpack.tf/item/5249701429 (#1-6)

https://backpack.tf/item/5213177464 (#7)

https://backpack.tf/item/5206305525 (#8 & #9)

https://backpack.tf/item/5204249055 - marketplace

#1

Bulk for Arcana Buccaneer’s Bicorne

https://backpack.tf/profiles/76561198157196963#!/compare/1532044800/1532131200

https://backpack.tf/profiles/76561198155219465#!/compare/1532044800/1532131200

#2

Bulk for Duped Misty Le party Phantom

https://backpack.tf/profiles/76561198155219465#!/compare/1532390400/1532563200

https://backpack.tf/profiles/76561198047941585#!/compare/1532563200/1532649600

#3

Untraceable, sold to scrap

https://backpack.tf/profiles/76561198056531196#!/compare/1533859200/1533945600

https://backpack.tf/profiles/76561198135388328#!/compare/1533859200/1533945600

#4

Untraceable, bought from scrap

https://backpack.tf/profiles/76561198135388328#!/compare/1533859200/1533945600

https://backpack.tf/profiles/76561198088764747#!/compare/1533859200/1533945600

#5

Untraceable, sold to scrap

https://backpack.tf/profiles/76561198240537922#!/compare/1534377600/1534464000

https://backpack.tf/profiles/76561198135388328#!/compare/1534464000/1534550400

#6

Untraceable, bought from scrap

https://backpack.tf/profiles/76561198135388328#!/compare/1534464000/1534550400

https://backpack.tf/profiles/76561198068844434#!/compare/1534464000/1534550400

#7

Backpack purchase

https://backpack.tf/profiles/76561198062898518#!/compare/1538265600/1538524800

https://backpack.tf/profiles/76561198086948995#!/compare/1538438400/1538524800

#8

Bulk for Purple Energy Beanie

https://backpack.tf/profiles/76561198077875601#!/compare/1537228800/1537315200

https://backpack.tf/profiles/76561198097171432#!/compare/1537228800/1537315200

#9

Bulk for Purple Energy Tough Stuff Muffs

https://backpack.tf/profiles/76561198097171432#!/compare/1537488000/1537574400

https://backpack.tf/profiles/76561198155066949#!/compare/1537142400/1537574400

Sellers:

https://i.imgur.com/L9OIIAj.png

https://backpack.tf/item/5206305525 - 50 keys

https://backpack.tf/item/5204249055 - 55 keys

https://backpack.tf/item/5213177464 - 56 keys

https://backpack.tf/item/5267874837 - 60 keys

Sales at:

37

40

Going with 37-40.