https://marketplace.tf/items/tf2/30375;5;u62

$79.99 / $1.81 = 44.19 keys

$79.99 / $1.82 = 43.95 keys

$79.99 / $1.84 = 43.47 keys

$79.99 / $1.87 = 42.78 keys

https://backpack.tf/item/10182320732

https://backpack.tf/item/8920701137

https://backpack.tf/item/4962542120

https://backpack.tf/profiles/76561198157207366#!/compare/1631664000/1631836800

https://backpack.tf/profiles/76561198064658655#!/compare/1631750400/1631836800

35 keys https://gyazo.com/4a0b5fe601f1aa5d0174d1c7d5bca96b

https://backpack.tf/profiles/76561198263836417#!/compare/1630713600/1630800000

https://backpack.tf/profiles/76561198064658655#!/compare/1630713600/1630800000

Bulk, but I wrote it down as 35 keys

https://backpack.tf/profiles/76561198361057294#!/compare/1631059200/1631145600

https://backpack.tf/profiles/76561198064658655#!/compare/1631059200/1631145600

38 keys

https://backpack.tf/profiles/76561198841279602#!/compare/1632787200/1632873600

https://backpack.tf/profiles/76561198078375939#!/compare/1632787200/1632873600

Untraceable

https://backpack.tf/profiles/76561198078375939#!/compare/1632787200/1632873600

https://backpack.tf/profiles/76561199117142644#!/compare/1632700800/1632873600

Untraceable

https://backpack.tf/profiles/76561198064711163#!/compare/1629590400/1630195200

https://backpack.tf/profiles/76561198166326970#!/compare/1630022400/1630195200

32 keys

https://backpack.tf/profiles/76561198166326970#!/compare/1630022400/1630195200

https://backpack.tf/profiles/76561198337734785#!/compare/1630108800/1630195200

34 keys and 17 keys

https://backpack.tf/profiles/76561198337734785#!/compare/1631750400/1631836800

https://backpack.tf/profiles/76561198064658655#!/compare/1631836800/1631923200

36 keys https://gyazo.com/4a0b5fe601f1aa5d0174d1c7d5bca96b

Buyers to 35.5 keys https://gyazo.com/ec650a5799766f349f290e2ce8b4cfb6

Sales

32

34

35

35

36

38

43

43

44

44

Buyers to 35.5 so I'll go with 36-44 keys

It still covers half the data points, and 34-36 are so close anyway that this small price difference shouldn't matter