Sale 1:

Sold with <1 key in items for Green Energy Airdog (~27.5)

Seller: https://backpack.tf/profiles/76561198090999398#!/compare/1544832000/1544918400

Buyer: https://backpack.tf/profiles/76561198008073880#!/compare/1544832000/1544918400

The skin is less than half a key: https://steamcommunity.com/market/listings/440/Strange%20Horror%20Holiday%20War%20Paint%20%28Field-Tested%29

X = 27

Sale 2:

Sold for Dead Presidents Engineer’s Cap (Suggestion at 13.5) + 12 keys

Seller: https://backpack.tf/profiles/76561198242646048#!/compare/1541721600/1541808000

Buyer: https://backpack.tf/profiles/76561198130439878#!/compare/1541548800/1541721600

https://backpack.tf/item/7271718103

X = 26

Sale 3:

Sold for Stormy Storm Warhood (Suggestion at 18) + 7 keys

Seller: https://backpack.tf/profiles/76561198130439878#!/compare/1544659200/1544745600

Buyer: https://backpack.tf/profiles/76561198090999398#!/compare/1544659200/1544745600

https://backpack.tf/item/7271718103

X = 26

Sale 4:

Sold for 22 keys + 2 ref

Seller: https://backpack.tf/profiles/76561198311498888#!/compare/1543276800/1543363200

Buyer: https://backpack.tf/profiles/76561198446606701#!/compare/1543104000/1543363200

https://backpack.tf/item/6820440211

X = 22

Sale 5:

Quicksold for 21 keys

Seller: https://backpack.tf/profiles/76561198351184262#!/compare/1541548800/1541635200

Buyer: https://backpack.tf/profiles/76561198242646048#!/compare/1541548800/1541635200

https://backpack.tf/item/7271718103

X = 21

Sale 6:

Quicksold for 21 keys

Seller: https://backpack.tf/profiles/76561198367196346#!/compare/1542931200/1543017600

Buyer: https://backpack.tf/profiles/76561198269408400#!/compare/1543017600/1543104000

https://backpack.tf/item/6810181270

X = 21

Sale 7:

Untraceable

Seller: https://backpack.tf/profiles/76561198088488150#!/compare/1542844800/1542931200

Buyer: https://backpack.tf/profiles/76561198390494996#!/compare/1542844800/1542931200

https://backpack.tf/item/6810181270

Sale 8:

Untraceable, only the Cranium matches

Seller: https://backpack.tf/profiles/76561198390494996#!/compare/1542931200/1543017600

Buyer: https://backpack.tf/profiles/76561198074178367#!/compare/1542931200/1543017600

https://backpack.tf/item/6810181270

Sale 9:

Untraceable, only 12 keys match

Seller: https://backpack.tf/profiles/76561198074178367#!/compare/1542931200/1543017600

Buyer: https://backpack.tf/profiles/76561198367196346#!/compare/1542931200/1543017600

https://backpack.tf/item/6810181270

Sale 10:

Sold for Strange Bubbling Tundra Top + 4 keys?

Seller: https://backpack.tf/profiles/76561198312670465#!/compare/1541462400/1541548800

Buyer: https://backpack.tf/profiles/76561198118922746#!/compare/1541462400/1541548800

https://backpack.tf/item/7271718103

Not confident about this sale.

Sale 11:

Untraceable

Seller: https://backpack.tf/profiles/76561198118922746#!/compare/1541462400/1541548800

Buyer: https://backpack.tf/profiles/76561198351184262#!/compare/1541462400/1541548800

https://backpack.tf/item/7271718103

Stormy Warhood:

https://backpack.tf/suggestion/5c2057fdcf6c7534277ee0e3

Dead Presidents Engineer’s Cap:

https://backpack.tf/suggestion/5c204935cf6c75291a18357a

Sellers:

https://i.imgur.com/M3mAzaq.png

https://backpack.tf/item/7271718103 - ~29.9 keys

https://backpack.tf/item/5694129231 - 30 keys

Sales at:

21 (2x)

22

26 (2x)

27

21 quicksold, excluding 21.

Going with 22-27.