History 1: https://backpack.tf/item/5264002744

55 keys match in buyer's compare:

https://backpack.tf/profiles/76561198258257749#!/compare/1628640000/1628726400

https://backpack.tf/profiles/76561198019257028#!/compare/1628640000/1628726400

History 2 (duped): https://backpack.tf/item/1887582234

52 keys:

https://backpack.tf/profiles/76561198087945631#!/compare/1628812800/1628899200

https://backpack.tf/profiles/76561198056823555#!/compare/1628726400/1628812800

History 3: https://backpack.tf/item/7452526587

Bulk:

https://backpack.tf/profiles/76561198086081600#!/compare/1630800000/1630886400

https://backpack.tf/profiles/76561198204215085#!/compare/1630800000/1630886400

1:1 for a Hellish Inferno Taunt: Kazotsky Kick:

https://backpack.tf/profiles/76561198204215085#!/compare/1630886400/1630972800

https://backpack.tf/profiles/76561198429068719#!/compare/1630886400/1630972800

could use there

History 4: https://backpack.tf/item/7437450312

first sale is mp

75 keys:

https://backpack.tf/profiles/76561198075229699#!/compare/1630281600/1630454400

https://backpack.tf/profiles/76561198067946670#!/compare/1630368000/1630454400

https://marketplace.tf/items/tf2/463;5;u3038

$199.99 / $1.81 = 110.49 keys ~110 keys

$199.99 / $1.81 = 110.49 keys ~110 keys

$199.99 / $1.84 = 108.69 keys ~109 keys

Sales at 52, 55, 75, 109, 110, 110

one of those mp sales re-sold for 75

52 was a dupe sale so I'll exclude it. the 110-ish Marketplace sales seem pretty far apart from the pure sales so I'll cut those off too

Going with 55-75 keys for now