Resuggestion, thanks Shuffle Spy

https://backpack.tf/item/6872577965

Untraceable:

https://backpack.tf/profiles/76561198171447086#!/compare/1606435200/1606521600

https://backpack.tf/profiles/76561199098694108#!/compare/1606435200/1606521600

https://backpack.tf/item/6512455459

untraceable:

https://backpack.tf/profiles/76561198088084435#!/compare/1604880000/1604966400

https://backpack.tf/profiles/76561199004803157#!/compare/1604793600/1604880000

https://backpack.tf/item/6480356069

deposited and withdrawn by same person

https://backpack.tf/item/4973825100

Unusualified by the most recent owner

https://backpack.tf/item/4094602403

Untraceable:

https://backpack.tf/profiles/76561199043553132#!/compare/1602115200/1602288000

https://backpack.tf/profiles/76561198097691073#!/compare/1601251200/1602201600

Bulk

https://backpack.tf/profiles/76561198097691073#!/compare/1602460800/1602547200

https://backpack.tf/profiles/76561198024694313#!/compare/1602201600/1602547200

Untraceable:

https://backpack.tf/profiles/76561198024694313#!/compare/1602547200/1602806400

https://backpack.tf/profiles/76561199012777365#!/compare/1596326400/1604448000

https://backpack.tf/item/3391610585

https://marketplace.tf/items/tf2/1118;5;u3009

November 16: $29.7/1.77=16.78 ~17 keys

Bulk/dumped to Tradeit.gg

https://backpack.tf/profiles/76561198299702199#!/compare/1605571200/1608076800

https://backpack.tf/profiles/76561198298504614#!/compare/1607990400/1608249600

https://backpack.tf/item/3192474355

untraceable:

https://backpack.tf/profiles/76561198152114850#!/compare/1601856000/1602201600

https://backpack.tf/profiles/76561198299987891#!/compare/1602115200/1602201600

https://backpack.tf/item/2946096256

bulk:

https://backpack.tf/profiles/76561198064658655#!/compare/1607990400/1608076800

https://backpack.tf/profiles/76561199100906514#!/compare/1607990400/1608076800

https://backpack.tf/item/2854778629

Untraceable:

https://backpack.tf/profiles/76561198412187692#!/compare/1604448000/1608076800

https://backpack.tf/profiles/76561198297034962#!/compare/1604534400/1605571200

Other Marketplace.tf sales which wern't mentioned above becasue they aren't traceable via histories:

September 21: $30/1.85=16.22 ~16 keys

October 22: $20.26/1.86=10.89 ~11 keys

additional info by Shuffle Spy:

https://cdn.discordapp.com/attachments/633536990054449172/800848766898405406/50cc6bf85784cd825fcf5c46346934c0.png - Sold for 15 Keys

https://imgur.com/a/yzxNtcA - Seller at 14 Keys and a 1 month (or older) seller at 15 Keys

https://backpack.tf/item/3372250608

https://backpack.tf/item/2946096256

I'd exclude 16 as it was fairly old and is countered by the 1+ month seller at 15. 14 - 15 will work here.