https://backpack.tf/item/6296625981

Sale 1:

https://backpack.tf/profiles/76561198057452720#!/compare/1645142400/1645228800

https://backpack.tf/profiles/76561198000247762#!/compare/1645142400/1645228800

Looks like they added their Haunted Ghosts Battle Boonie (~34) for a Demonflame Tam O' Shanter, 884 - 34 = 850 keys, seems high given later sales

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Mini for Demonflame Tam O' Shanter:

https://backpack.tf/item/2033639173

https://backpack.tf/profiles/76561198244962432#!/compare/1645142400/1645228800

https://backpack.tf/profiles/76561198000247762#!/compare/1645056000/1645142400

Looks like they added 40 keys for Dupe Knifestorm Brain Bucket (924), 924 - 40 = 884 keys

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Mini for Dupe Knifestorm Brain Bucket:

https://backpack.tf/profiles/76561198244962432#!/compare/1646524800/1646611200

https://backpack.tf/profiles/76561198065906371#!/compare/1646438400/1646611200

Looks like Arcana Furious Fukaamigasa (495) + Memory Leak Blighted Beak (389) + Overclocked Dragonborn Helmet (40, https://backpack.tf/suggestion/628649304aa22a637d2b90f5) = 924 keys

Using some outdated sales from the clean version, seen in this suggestion: https://backpack.tf/suggestion/621c1a59ef1b7c71b56e3d2e, gives 517 - 894, ~706 keys

That would change Sale 1 to 706 - 40 - 34 = 632 keys, also supporting a lower value that would now fit in range

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Mini for Memory Leak Blighted Beak:

https://backpack.tf/profiles/76561198244962432#!/compare/1650931200/1651017600

https://backpack.tf/profiles/76561198132068284#!/compare/1650931200/1651017600

Frostbite One-Man Army (175) + Fifth Dimension A Hat to Kill For (110, outdated, this sale seems incomplete https://backpack.tf/profiles/76561198188093413#!/compare/1650067200/1650153600 https://gladiator.tf/listings/625b504bdc444e692760183c) + Spellbound Aspect Taunt: The Dueling Banjo (34 https://gladiator.tf/sales?item=Spellbound%20Aspect%20Taunt:%20The%20Dueling%20Banjo&at=2022-04-19T13:49:25.796Z) + 70 keys = 389 keys

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Sale 2:

https://backpack.tf/profiles/76561198000247762#!/compare/1645228800/1645315200

https://backpack.tf/profiles/76561198860735519#!/compare/1645315200/1645401600

Guessing it was the Nuke + Boonie (from above) + >500 keys for the Cloudy Moon Hat With No Name + Chiroptera Venenata Scotsman's Stove Pipe, bulk, still supports a lower value than sale 1

Sale 3:

https://backpack.tf/profiles/76561198860735519#!/compare/1651276800/1651363200

https://backpack.tf/profiles/76561198056531586#!/compare/1651276800/1651363200

https://gladiator.tf/time-machine?item=Strange%20Misty%20Skull%20Nuke&at=2022-05-01T11:27:21.000Z

Looks like Burning Flames Racc Mann (280) + Searing Plasma Airdog (~15 https://gladiator.tf/sales?item=Searing%20Plasma%20Airdog&at=2022-03-19T09:30:14.670Z) + Strange Lieutenant Bites (~6) + Strange Viking Braider (~1) + 202 keys = 504 keys

Sale 4:

https://backpack.tf/profiles/76561198056531586#!/compare/1652832000/1652918400

https://backpack.tf/profiles/76561198431725617#!/compare/1652832000/1652918400

https://imgur.com/a/U6DBq7s

700 keys

Sales:

504, 700

Rounding to 500 - 700 keys.