Sale 1:

Sold for 9 keys + 28 ref

Seller: https://backpack.tf/profiles/76561198304138933#!/compare/1523059200/1523145600

Buyer: https://backpack.tf/profiles/76561198069118738#!/compare/1523059200/1523145600

Bot.tf confirms: https://i.imgur.com/LoQ3x7C.png

X = 10

Sale 2:

Sold for 9 keys + 27 ref

Seller: https://backpack.tf/profiles/76561198304138933#!/compare/1527638400/1527724800

https://backpack.tf/item/623911839 - Buyer can’t be identified yet

Bot.tf confirms: https://i.imgur.com/LoQ3x7C.png

X = 10

Sale 3:

Sold for 9 keys + ~0.5 keys in metal to a quickbuyer

Seller: https://backpack.tf/profiles/76561198126985704#!/compare/1520985600/1521072000

Buyer: https://backpack.tf/profiles/76561198349886701#!/compare/1520985600/1521072000

X = 9.5

Sale 4:

Sold to a bot for 9 keys + 12 ref

Seller: https://backpack.tf/profiles/76561198114782270#!/compare/1524528000/1524787200

Buyer: https://backpack.tf/profiles/76561198304138933#!/compare/1524700800/1524787200

Bot.tf confirms: https://i.imgur.com/LoQ3x7C.png

X = 9.5

Sale 5:

Sold for 9 keys + 8 ref (buyer’s end)

Seller: https://backpack.tf/profiles/76561198129797836#!/compare/1526688000/1526774400

Buyer: https://backpack.tf/profiles/76561198153806405#!/compare/1526688000/1526774400

X = 9.5

Sale 6:

Sold to a quickbuyer for 9 keys + 20 ref

Seller: https://backpack.tf/profiles/76561198131633162#!/compare/1522886400/1522972800

Buyer: https://backpack.tf/profiles/76561198029431277#!/compare/1522886400/1522972800

X = 9.5

Sale 7:

Sold for 9 keys + 12 ref

Seller: https://backpack.tf/profiles/76561198114545227#!/compare/1526342400/1526428800

Buyer: https://backpack.tf/profiles/76561198349886701#!/compare/1526342400/1526428800

X = 9.5

Sale 8:

Sold to a bot for 9 keys + 20 ref

Seller: https://backpack.tf/profiles/76561198131633162#!/compare/1522281600/1522368000

Buyer: https://backpack.tf/profiles/76561198304138933#!/compare/1522281600/1522368000

Bot.tf confirms: https://i.imgur.com/LoQ3x7C.png

X = 9.5

Sale 9:

Sold to a bot for 9 keys + 12 ref

Seller: https://backpack.tf/profiles/76561198796233706#!/compare/1527638400/1527811200

Buyer: https://backpack.tf/profiles/76561198304138933#!/compare/1527724800/1527811200

Bot.tf confirms: https://i.imgur.com/LoQ3x7C.png

X = 9.5

Sale 10:

Sold for 9 keys

Seller: https://backpack.tf/profiles/76561198141054773#!/compare/1527206400/1527292800

Buyer: https://backpack.tf/profiles/76561198796233706#!/compare/1527206400/1527292800

X = 9

Sale 11:

Sold for 8 keys + ~0.5 keys in metal

Seller: https://backpack.tf/profiles/76561198261202700#!/compare/1526515200/1526774400

Buyer: https://backpack.tf/profiles/76561198129797836#!/compare/1526688000/1526774400

X = 8.5

Sale 12:

Sold for $26.55 on marketplace.tf

https://marketplace.tf/items/359;5;u36

Gonna be a large outlier, excluding.

Sale 13:

Bulk for Mega Strike Bad Pipes, apparently.

Seller: https://backpack.tf/profiles/76561198024614290#!/compare/1520899200/1521072000

Buyer: https://backpack.tf/profiles/76561198126985704#!/compare/1520812800/1520899200

Sellers:

~9.6 keys:

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

https://backpack.tf/item/705582210

~9.7 keys:

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

https://backpack.tf/item/812079953

11 keys:

https://i.imgur.com/FKGg6LU.png

https://backpack.tf/item/504592244

Sales at:

8.5

9

9.5 (7x)

10 (2x)

8.5 looks low, excluding.

Going with 9-10.