I wouldn't kill for this.

https://backpack.tf/item/4435191248

Sale 1) Sold + Green Confetti Berlin Brain Bucket (18 Keys) for an Orbiting Fire Soldier's Stash (59 Keys)

https://backpack.tf/profiles/76561198193107411#!/compare/1525392000/1525478400

59 - 18 = 41 Keys

High outlier.

Brain Mini

https://backpack.tf/suggestion/5b0e47efcf6c75130c4a04f4 - 18 Keys

Stash Mini

https://backpack.tf/suggestion/5b10d5c444325a6e95537fc1 - 59 Keys

Sale 2) Sold for 26 Keys

https://backpack.tf/profiles/76561198042141730#!/compare/1526515200/1526688000

Sale 3) Sold for 27 Keys

https://backpack.tf/profiles/76561198188754881#!/compare/1526774400/1526860800

Sale 4) Sold for a Dead Presidents Sultan’s (9.5 Keys) + Bubbling Mirror + Purple Confetti Hetman’s (9 Keys)

https://backpack.tf/profiles/76561198188754881#!/compare/1526860800/1526947200

9.5 + 9 + 9 = 27.5, which rounds to 28 Keys

Mirror Mini

Sale #1

https://backpack.tf/profiles/76561198304138933#!/compare/1524693600/1524780000

9 keys 4 ref

https://imgur.com/a/TxQOYia

Rounds to 9 Keys

Sale #2

https://backpack.tf/profiles/76561198121830870#!/compare/1523232000/1523318400

https://backpack.tf/profiles/76561198389442066#!/compare/1523232000/1523318400

9 keys

Hetman’s Mini

https://backpack.tf/suggestion/5b0e54e944325a279e08a7e8 - 9 Keys

https://backpack.tf/item/5621776867

Sale 5) Sold for 26 Keys

https://backpack.tf/profiles/76561198021055079#!/compare/1524960000/1525046400

Credits to FallenCrown for the Mirror Mini.