Brain Matter

https://backpack.tf/item/419366452

Sale 1) Bulk sale

https://backpack.tf/profiles/76561198137563438#!/compare/1544486400/1544572800

https://backpack.tf/profiles/76561198215130228#!/compare/1544486400/1544572800

Sale 2) Sold in a day for 19 Keys

https://backpack.tf/profiles/76561198215130228#!/compare/1544572800/1544659200

Sale 3) Bulk sale

https://backpack.tf/profiles/76561198017534558#!/compare/1544659200/1544745600

Sale 4) Bulk sale

https://backpack.tf/profiles/76561198066582436#!/compare/1544745600/1544832000

Sale 5) Bulk sale

https://imgur.com/a/6N6qGMW - Thanks, r0b

Sale 6) ?

https://backpack.tf/profiles/76561198840748471#!/compare/1544745600/1544832000

https://backpack.tf/profiles/76561198261265788#!/compare/1544745600/1544832000

https://backpack.tf/item/941838044

Sale 7) Sold for 14 Keys + Cloud 9 Big Elfin Deal or for 23 Keys

https://backpack.tf/profiles/76561198006544512#!/compare/1540252800/1540339200

Don't know because the Purple Energy Sky High Fly Guy sold for the other one.

Sale 8) ?

https://backpack.tf/profiles/76561198121825886#!/compare/1540252800/1540339200

https://backpack.tf/profiles/76561198266876790#!/compare/1540252800/1540339200

https://backpack.tf/item/356679609

Sale 9) Sold for an Aces High Galvanized Gibus

https://backpack.tf/profiles/76561198254918432#!/compare/1541203200/1541289600

https://backpack.tf/profiles/76561198184961155#!/compare/1541203200/1542240000

This is better used for the Gibus.

Sale 10) Sold + Defragmenting Hard Hat 17% (~1.1 Keys) for a Steaming Salty Dog (23.5 Keys)

https://backpack.tf/profiles/76561198184961155#!/compare/1542240000/1542412800

https://backpack.tf/profiles/76561198254918432#!/compare/1542153600/1542412800

23.5 - 1.1 = 22.4, which rounds to 22 Keys

Salty Dog Mini

https://backpack.tf/suggestion/5c2b20d8cf6c7578be2e5284 - 23.5 Keys

https://backpack.tf/item/3327210581

Sale 11) Sold for $58.46 when Keys were ~$1.79 each

https://marketplace.tf/items/388;5;u15;strange

https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

58.46 / 1.79 = 32.66 Keys. High outlier.