Sale 1:

Sold for 26 keys

Seller: https://backpack.tf/profiles/76561198055847835#!/compare/1505520000/1505606400

Buyer: https://backpack.tf/profiles/76561198261766530#!/compare/1505606400/1505692800

X = 26

Sale 2:

Sold for 23 keys

Seller: https://backpack.tf/profiles/76561198192602363#!/compare/1508198400/1508284800

Buyer: https://backpack.tf/profiles/76561198255640609#!/compare/1508284800/1508630400

X = 23

Sale 3:

Sold for 20 keys + Strange Spec. KS Knife (1)

Seller: https://backpack.tf/profiles/76561198195731583#!/compare/1504915200/1505001600

Buyer: https://backpack.tf/profiles/76561198211313779#!/compare/1504915200/1505001600

X = 21

Sale 4:

Sold for Stormy Storm Helmet Without a Home (Suggestion at 12) + 8 keys

http://www.tf2outpost.com/trade/29431021 - B/O of 22

Seller: https://backpack.tf/profiles/76561198063857721#!/compare/1510012800/1510099200

Buyer: https://backpack.tf/profiles/76561198114312016#!/compare/1510012800/1510099200

X = 20

Sale 5:

Sold for 9 keys + Dead Presidents Dread Knot

http://www.tf2outpost.com/trade/29427693 - No B/O

Seller: https://backpack.tf/profiles/76561198160856661#!/compare/1510012800/1510099200

Buyer: https://backpack.tf/profiles/76561198063857721#!/compare/1510012800/1510099200

Seems low, excluding.

Sale 6:

Weird bulk sale

Seller: https://backpack.tf/profiles/76561198146032023#!/compare/1509235200/1509321600

Buyer: https://backpack.tf/profiles/76561198294595859#!/compare/1509235200/1509321600

Sale 7:

Sold for Starstorm Slumber Airdog

Seller: https://backpack.tf/profiles/76561198155433364#!/compare/1508803200/1508889600

buyer: https://backpack.tf/profiles/76561198132226518#!/compare/1508803200/1508889600

Can be used on the Air, dog.

Stormy Storm Helmet Without a Home:

https://backpack.tf/suggestion/5a0a7d66cf6c7553b51db301

Sellers:

25 keys:

https://i.imgur.com/q881zlq.png - young

Sales at:

20

21

23

26

Going with 20-26.