Using last month

Sale 1:

Bot.tf sale at 5 keys + 9.66 ref

Seller: https://backpack.tf/profiles/76561198442764620#!/compare/1524009600/1524096000

Buyer: https://backpack.tf/profiles/76561198809718054#!/compare/1523923200/1524009600

Bot.tf confirms: https://i.imgur.com/P6JAsMH.png

X = 5.5

Sales 2 & 3:

Two more bot.tf sales at ~5.5 keys:

https://i.imgur.com/P6JAsMH.png

Here's one of them:

Seller: https://backpack.tf/profiles/76561198308819102#!/compare/1523923200/1524009600

Buyer: https://backpack.tf/profiles/76561198223981756#!/compare/1523923200/1524009600

Here's the other

Seller: https://backpack.tf/profiles/76561198308819102#!/compare/1523664000/1523750400

Buyer: https://backpack.tf/profiles/76561198191571421#!/compare/1523577600/1523750400

Can't tell the two apart, however.

X = 5.5 (2x)

Sale 4:

Sold for 5 keys (Buyer's compare link)

Seller: https://backpack.tf/profiles/76561198048851745#!/compare/1524009600/1524096000

Buyer: https://backpack.tf/profiles/76561198010245943#!/compare/1524009600/1524096000

X = 5

Sale 5:

Sold for 5 keys

Seller: https://backpack.tf/profiles/76561198259342040#!/compare/1523232000/1523318400

Buyer: https://backpack.tf/profiles/76561198386348408#!/compare/1523145600/1523318400

X = 5

Sellers:

6 keys:

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

https://backpack.tf/item/6563835429

https://i.imgur.com/G2a3dpj.png

https://backpack.tf/item/6252747578

14 keys:

https://i.imgur.com/i5PNUIf.png

https://backpack.tf/item/6356870438

Sales at:

5 (2x)

5.5 (3x)