Sale 1:

Sold for 4 keys

Seller: https://backpack.tf/profiles/76561198094183864#!/compare/1530921600/1531094400

Buyer: https://backpack.tf/profiles/76561198009089083#!/compare/1530921600/1531267200

X = 4

Sale 2:

Sold for 4 keys

Seller: https://backpack.tf/profiles/76561198312583107#!/compare/1531440000/1531526400

Buyer: https://backpack.tf/profiles/76561198323762984#!/compare/1531526400/1531612800

Bot.tf confirms: https://i.imgur.com/spwDNCE.png

X = 4

Sale 3:

Sold for 4 keys?

Seller: https://backpack.tf/profiles/76561198312583107#!/compare/1531094400/1531180800

Buyer: https://backpack.tf/profiles/76561198131526809#!/compare/1531094400/1531267200

Untraceable, but bot.tf confirms: https://i.imgur.com/spwDNCE.png

X = 4?

Sale 4:

Sold to a bot for 3 keys + 10 ref?

Seller: https://backpack.tf/profiles/76561198105520850#!/compare/1530921600/1531094400

Buyer: https://backpack.tf/profiles/76561198312583107#!/compare/1531008000/1531094400

Untraceable, but bot.tf confirms: https://i.imgur.com/spwDNCE.png

X = 3.5?

Sale 5:

Sold for $11.39 on marketplace.tf

https://marketplace.tf/items/1114;5;u3004

Will end up being pretty high, excluding.

Sale 6:

Bulk for Green Confetti Vive La France

Seller: https://backpack.tf/profiles/76561198262354524#!/compare/1530057600/1530144000

Buyer: https://backpack.tf/profiles/76561198165055074#!/compare/1530057600/1530144000

Sale 7:

Bulk for Infernal Smoke Zoomin’ Broom

Seller: https://backpack.tf/profiles/76561198123225617#!/compare/1530748800/1530835200

Buyer: https://backpack.tf/profiles/76561198094183864#!/compare/1530748800/1530835200

Sale 8:

Bulk for Vivid Sky High Fly Guy

Seller: https://backpack.tf/profiles/76561198165055074#!/compare/1530144000/1530230400

Buyer: https://backpack.tf/profiles/76561198304343915#!/compare/1530144000/1530230400

Sellers:

~4.15 keys:

https://i.imgur.com/4hT4rIb.png

https://backpack.tf/item/5752421835

~4.35 keys:

https://i.imgur.com/hssIr7h.png

https://backpack.tf/item/6783389822

https://backpack.tf/item/3974071706

~5.45 keys:

https://i.imgur.com/9w56l1Z.png

https://backpack.tf/item/2896285980

9 keys:

https://i.imgur.com/paTXlW8.png

https://backpack.tf/item/3730497980

10 keys:

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

https://backpack.tf/item/2716975224

Sales at:

4 (2x)

And untraceable sales at 3.5 and 4.

Going with 4 flat.