Sale 1:

Sold with ~5.5 keys in items for Neutron Star Galvanized Gibus (44.5)

http://www.tf2outpost.com/trade/29731583 - B/O of 36

https://backpack.tf/profiles/76561198083047491#!/compare/1533254400/1533340800

https://backpack.tf/profiles/76561198454504440#!/compare/1533254400/1533340800

https://backpack.tf/item/6142861316

X = 36 (Capped by B/O)

Sale 2:

Sold for Haunted Ghosts Big Elfin Deal (22.5) + 6 keys

No B/O

Seller: https://backpack.tf/profiles/76561198067741299#!/compare/1533254400/1533340800

Buyer: https://backpack.tf/profiles/76561198083047491#!/compare/1533254400/1533340800

https://backpack.tf/item/6142861316

X = 29

Sale 3:

Sold for 23 keys (Buyer’s end)

Seller: https://backpack.tf/profiles/76561198337734785#!/compare/1536192000/1536278400

Buyer: https://backpack.tf/profiles/76561198080972676#!/compare/1535328000/1536278400

https://backpack.tf/item/6906808067

X = 23

Sale 4:

Sold for 22 keys

Seller: https://backpack.tf/profiles/76561198306288794#!/compare/1535673600/1535760000

Buyer: https://backpack.tf/profiles/76561198068189558#!/compare/1535241600/1535760000

https://backpack.tf/item/6142861316

X = 22

Sale 5:

Bought from scrap.tf for 21 keys + some metal

Seller: https://backpack.tf/profiles/76561198135388328#!/compare/1535760000/1535846400

Buyer: https://backpack.tf/profiles/76561198350910856#!/compare/1535846400/1535932800

https://backpack.tf/item/6142861316

X = 21

Other Sales:

https://backpack.tf/item/6142861316 (all untraceable sales below)

#1

Untraceable

https://backpack.tf/profiles/76561198337734785#!/compare/1533168000/1533254400

https://backpack.tf/profiles/76561198004789112#!/compare/1533168000/1533254400

only 10 ref matches

#2

Sold for Lantern Bubble Pipe?

https://backpack.tf/profiles/76561198004789112#!/compare/1533254400/1533340800

https://backpack.tf/profiles/76561198067741299#!/compare/1533254400/1533340800

Can’t tell if anything was added with the Warhood, but if nothing was added, it would be better to not use this sale, as there’s no B/O here.

#3

Bulk for Stormy 13th Hour Baker Boy

https://backpack.tf/profiles/76561198454504440#!/compare/1533600000/1533686400

https://backpack.tf/profiles/76561198255903931#!/compare/1533600000/1533686400

#4

Bulk for Bonzo Attendant

https://backpack.tf/profiles/76561198255903931#!/compare/1533859200/1533945600

https://backpack.tf/profiles/76561198211518224#!/compare/1533686400/1533945600

#5

Bulk for Duped Green Energy Towering Pillar of Hats

https://backpack.tf/profiles/76561198211518224#!/compare/1533945600/1534291200

https://backpack.tf/profiles/76561198306288794#!/compare/1533859200/1533945600

#6

Sold for Cool Uranium Bazaar Bargain

https://backpack.tf/profiles/76561198068189558#!/compare/1535241600/1535760000

https://backpack.tf/profiles/76561198346734072#!/compare/1535673600/1535760000

#7

Untraceable, sold to scrap

https://backpack.tf/profiles/76561198346734072#!/compare/1535760000/1535932800

https://backpack.tf/profiles/76561198135388328#!/compare/1535760000/1535846400

Sales at:

21

22

23

29

36

36 is an outlier, excluding 36.

Going with 21-29.