Resuggestion from https://backpack.tf/suggestion/5f3c829e9411df733b06e998

With additional proof

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Credits to Mockingbird

and credits to for the previous suggestion https://backpack.tf/u/76561198151811573

Sale 1:

https://marketplace.tf/items/tf2/15054;15;u704;w3;pk54;kt-2;festive

https://backpack.tf/item/4087456127

Aug 8: $111.11/1.85 = 60k

Sale 2:

https://marketplace.tf/items/tf2/15054;5;u704;w3;pk54;kt-2

25 Jul: 140/1.93 = 73

Sale 3 & 4:

https://marketplace.tf/items/tf2/15054;15;u704;w3;pk54;kt-1

26 Jun: 62/2.03 = 30

1 Jul: 140/ 2.02 = 69

Sale 5:

https://backpack.tf/profiles/76561198065156103#!/compare/1594425600/1596153600

https://backpack.tf/profiles/76561197993151025#!/compare/1594425600/1594512000

untrace

30 excluded as is outlier

60-73

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Proof by https://backpack.tf/u/76561197964393843

Sale 5 was for 56 keys (IDs match). Buyer's side is this one:

https://backpack.tf/profiles/76561197993151025#!/compare/1594771200/1596153600

Another sale here that should fall in range:

https://backpack.tf/profiles/76561197982127154#!/compare/1594425600/1594512000

https://backpack.tf/profiles/76561198090251227#!/compare/1594339200/1594425600

So 56-73 will work.

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Proof by me

https://backpack.tf/item/3964290314

https://marketplace.tf/items/tf2/15054;15;u704;w3;pk54;kt-1

I quickbought it off MP for $100 / $1.83 = 54.64 keys

https://marketplace.tf/items/tf2/15054;5;u704;w3;pk54;kt-1

Sold for $160 = 86 keys

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Sales

30

55

56

60

69

73

86

My $100 buy was a quickbuy, bought as soon as it was listed

but as it is, that sale supports a lower value and despite my $160 sale being the most recent, it looks very high in hindsight - Going with 55-73 keys