Using last month.

Sale 1:

Sold for 7 keys

Seller: https://backpack.tf/profiles/76561198363395191#!/compare/1530835200/1530921600

Buyer: https://backpack.tf/profiles/76561197977240054#!/compare/1530403200/1531008000

This bot is not a bot.tf bot, so no need to check for confirmation there.

X = 7

Sale 2:

Sold for 6 keys + 30 ref?

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

Buyer: https://backpack.tf/profiles/76561198174084635#!/compare/1529798400/1531526400

Untraceable, apart from 27 ref on the seller’s end and 3 keys on the buyer’s end. Bot.tf confirms, but it is unreliable. https://i.imgur.com/kQKmsyK.png

X = 7?

Sale 3:

Sold for 6 keys + 30 ref?

Seller: https://backpack.tf/profiles/76561198312583107#!/compare/1531180800/1531267200

Buyer: https://backpack.tf/profiles/76561198090636918#!/compare/1530662400/1531267200

Untraceable, apart from some ref. Bot.tf confirms, but it is unreliable. https://i.imgur.com/kQKmsyK.png

X = 7?

Sale 4:

Sold for 6 keys + ~0.5 keys in metal (Buyer’s compare link)

Seller: https://backpack.tf/profiles/76561198205329240#!/compare/1532390400/1532476800

Buyer: https://backpack.tf/profiles/76561198080714435#!/compare/1532476800/1532563200

X = 6.5

Sale 5:

Sold for 6 keys

Seller: https://backpack.tf/profiles/76561198071920700#!/compare/1532304000/1532390400

Buyer: https://backpack.tf/profiles/76561198048589995#!/compare/1532217600/1532390400

X = 6

Sale 6:

Sold for 6 keys

Seller: https://backpack.tf/profiles/76561198382589541#!/compare/1530403200/1530489600

Buyer: https://backpack.tf/profiles/76561198005032783#!/compare/1530403200/1530489600

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

X = 6

Sale 7:

Sold for 6 keys

Seller: https://backpack.tf/profiles/76561198305676157#!/compare/1532131200/1532217600

Buyer: https://backpack.tf/profiles/76561198048589995#!/compare/1532044800/1532217600

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

X = 6

Sale 8:

Sold to a bot for 6 keys + 8 ref?

Seller: https://backpack.tf/profiles/76561198035547951#!/compare/1530748800/1530835200

Buyer: https://backpack.tf/profiles/76561198312583107#!/compare/1530489600/1530748800

Untraceable. Bot.tf confirms, but it is unreliable. https://i.imgur.com/kQKmsyK.png

X = 6?

Sale 9:

Sold to a bot for 5 keys + 6.11 ref?

Seller: https://backpack.tf/profiles/76561198815593082#!/compare/1532131200/1532217600

Buyer: https://backpack.tf/profiles/76561198305676157#!/compare/1532131200/1532217600

Untraceable, apart from 1 key and all the metal. However, seeing as the exact amount of metal was involved, I don’t doubt that it sold for full pure here, so I’d be willing to trust bot.tf’s stats here. https://i.imgur.com/kQKmsyK.png

X = 5

Sale 10:

Sold to a bot for 5 keys

Seller: https://backpack.tf/profiles/76561198028853818#!/compare/1530403200/1530489600

Buyer: https://backpack.tf/profiles/76561198363395191#!/compare/1530316800/1530403200

This bot is not a bot.tf bot, so no need to check for confirmation there.

X = 5

Sale 11:

Sold to a bot for 5 keys

Seller: https://backpack.tf/profiles/76561198846146550#!/compare/1532563200/1532649600

Buyer: https://backpack.tf/profiles/76561198382589541#!/compare/1532390400/1532563200

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

Excluding this sale, however, as the seller is an obvious scammer alt/marketplace.tf bot impersonator.

Sale 12:

Bulk

Seller: https://backpack.tf/profiles/76561198024867201#!/compare/1531353600/1531440000

Buyer: https://backpack.tf/profiles/76561198058742814#!/compare/1531440000/1531526400

Sale 13:

Bulk for Green Confetti Balloonihoodie

Seller: https://backpack.tf/profiles/76561198262354524#!/compare/1531008000/1531180800

Buyer: https://backpack.tf/profiles/76561198093926010#!/compare/1531094400/1531180800

Sellers:

7 keys:

https://i.imgur.com/vY5lbq6.png

https://backpack.tf/item/6865947338

https://backpack.tf/item/4534940695

8 keys:

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

https://backpack.tf/item/4440818050

https://backpack.tf/item/5930198121

10 keys:

https://i.imgur.com/sd6QQPP.png

https://backpack.tf/item/4488472926

11 keys:

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

https://backpack.tf/item/4438557534

12 keys:

https://i.imgur.com/KgnQ4NR.png

https://backpack.tf/item/4528120995

Sales at:

5 (2x)

6 (3x)

6.5

7

And untraceable sales at 7 (2x) and 6.

5 went to bots, and isn’t too common. Excluding 5.

Going with 6-7.