Using last month.

Sale 1:

Sold for 13 keys + ~1 key in ref

Seller: https://backpack.tf/profiles/76561198335791307#!/compare/1539302400/1539388800

Buyer: https://backpack.tf/profiles/76561198045447325#!/compare/1539302400/1539388800

https://backpack.tf/item/6575645802

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

X = 14

Sale 2:

Sold for 13 keys

Seller: https://backpack.tf/profiles/76561198312583107#!/compare/1538870400/1538956800

Buyer: https://backpack.tf/profiles/76561198108650109#!/compare/1538870400/1538956800

https://backpack.tf/item/6461060256

X = 13

Sale 3:

Sold for 13 keys

Seller: https://backpack.tf/profiles/76561197961643548#!/compare/1537833600/1538092800

Buyer: https://backpack.tf/profiles/76561198160861401#!/compare/1538006400/1538092800

https://backpack.tf/item/6953167257

X = 13

Sale 4:

Sold for 10 keys to a bot?

Seller: https://backpack.tf/profiles/76561198294431910#!/compare/1537574400/1537660800

Buyer: https://backpack.tf/profiles/76561198335791307#!/compare/1537574400/1537660800

https://backpack.tf/item/6575645802

Looks as if the seller spent the keys on the slumber wing mann before their backpack was scanned, because we see key on the buyer’s end going to the last owner of the wing mann. With that in mind, I’m positive that it sold for 10 keys here.

X = 10

Other Sales:

https://backpack.tf/item/6756961756 (#1)

https://backpack.tf/item/6618186076 (#2)

https://backpack.tf/item/6575645802 (#3)

https://backpack.tf/item/6567957322 (#4)

https://backpack.tf/item/6482439173 (#5 & #6)

https://backpack.tf/item/6549837903 - not unusual at the time

https://backpack.tf/item/6465843803 - tf2mart

#1

Untraceable

https://backpack.tf/profiles/76561198048246257#!/compare/1538006400/1538092800

https://backpack.tf/profiles/76561198044684270#!/compare/1538006400/1538092800

#2

SCM

https://backpack.tf/profiles/76561198124728984#!/compare/1537228800/1537488000

https://backpack.tf/profiles/76561198804073182#!/compare/1538179200/1538524800

#3

Sold for a regular runner’s rhythm

https://backpack.tf/profiles/76561198391635943#!/compare/1537401600/1538006400

https://backpack.tf/profiles/76561198294431910#!/compare/1537315200/1537574400

#4

Untraceable

https://backpack.tf/profiles/76561198155118706#!/compare/NaN/1539475200

https://backpack.tf/profiles/76561198335791307#!/compare/1539388800/1539475200

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

#5

Untraceable

https://backpack.tf/profiles/76561198121326369#!/compare/1537315200/1537747200

https://backpack.tf/profiles/76561197997810328#!/compare/1537056000/1537747200

#6

Untraceable

https://backpack.tf/profiles/76561197997810328#!/compare/1537747200/1537833600

https://backpack.tf/profiles/76561198334598690#!/compare/1537747200/1537833600

https://i.imgur.com/4iABwWQ.png - labelled as 10 keys

Sellers:

https://i.imgur.com/92HxzYv.png

https://backpack.tf/item/6567957322 - ~13.75 keys

https://backpack.tf/item/6463974087 - ~13.75 keys

https://backpack.tf/item/6482439173 - 18 keys

Sales at:

10

13 (2x)

14

Going to keep 10, as bot.tf records several purchases at ~9.5-10, even if some of them are untraceable.

Going with 10-14.