Sale 1:

Sold for 20 keys

Seller: https://backpack.tf/profiles/76561198021055079#!/compare/1552089600/1552176000

Buyer: https://backpack.tf/profiles/76561198323241116 - no compare available

https://backpack.tf/item/3332568654

https://i.imgur.com/CI8PBZX.png

https://i.imgur.com/6YqqSqb.png

X = 20

Sale 2:

Sold for Death at Dusk Pug (17.5)

Seller: https://backpack.tf/profiles/76561198061440669#!/compare/1550275200/1550361600

Buyer: https://backpack.tf/profiles/76561198078578085#!/compare/1550188800/1550361600

https://backpack.tf/item/3332568654

X = 18

Sale 3:

Sold to my buy order for 13 keys

Seller: https://backpack.tf/profiles/76561198147671424#!/compare/1550534400/1550880000

Buyer: https://backpack.tf/profiles/76561198021055079#!/compare/1550793600/1550880000

https://backpack.tf/item/3332568654

https://i.imgur.com/psYoP9B.png

https://i.imgur.com/36TnLoP.png

X = 13

Other Sales:

https://backpack.tf/item/2214004261 (#1)

https://backpack.tf/item/3332568654 (#2 & #3)

#1

Untraceable

https://backpack.tf/profiles/76561198353692140#!/compare/1546473600/1546560000

https://backpack.tf/profiles/76561198072411295#!/compare/1546646400/1547596800

#2

Untraceable

https://backpack.tf/profiles/76561198042607131#!/compare/1518220800/1552348800

https://backpack.tf/profiles/76561198061440669#!/compare/1550275200/1550361600

#3

Sold for Circling TF Logo Climbing Commander

https://backpack.tf/profiles/76561198078578085#!/compare/1550361600/1550448000

https://backpack.tf/profiles/76561198147671424#!/compare/1550361600/1550448000

Using on the Commander.

Sales at:

13

18

20

No current sellers.

13 went to my buy order, looks like an outlier, and is countered by current buyers. Excluding 13.

Going with 18-20.