Mini-trains again...

Item 1: https://backpack.tf/item/12487805527

Sale 1: Bulk sale

https://backpack.tf/profiles/76561198859721638#!/compare/1753833600/1753920000

https://backpack.tf/profiles/76561197975508167#!/compare/1753833600/1753920000

Item 2: https://backpack.tf/item/12137923897

Sale 1: 15k pure (all keys share history)

https://backpack.tf/profiles/76561198261223846#!/compare/1753228800/1753315200

https://backpack.tf/profiles/76561198854496201#!/compare/1753228800/1753315200

Item 3: https://backpack.tf/item/11896098475

Sale 1: 18k pure

https://backpack.tf/profiles/76561199085116273#!/compare/1757548800/1757635200

https://backpack.tf/profiles/76561198016193899#!/compare/1757548800/1757635200

Item 4: https://backpack.tf/item/4953098550

Sale 1: Bulk/buyout

https://backpack.tf/profiles/76561199087203575#!/compare/1754784000/1754870400

https://backpack.tf/profiles/76561199745887780#!/compare/1754697600/1754956800

Item 5: https://backpack.tf/item/1431834497

This history is broken, or at the very least sale is untrace, Wilson has the item in his backpack with a 4 year gap, then back again, with no trace of it leaving despite it being in Luve's inventory.

Marketplace sale:

https://marketplace.tf/items/tf2/631;5;u12

Jul 8th for $34.99

https://marketplace.tf/items/tf2/5021;6

Key price for the day is $2.02

$34.99/$2.02 = 17.32 keys

Sales at 15 keys, 17.32 keys, and 18 keys

Rounding the 17.32 key sale to 17 keys.

Classifieds link: https://imgur.com/a/gXwKikD

Given that the 18 key listing is unsold for 2 months, I'd exclude this from the range.

Using the sales at 15 and 17 keys for the range.