Sales:

Item 1: https://backpack.tf/item/5154278541 - no recent sales

Item 2: https://backpack.tf/item/13272374270

Sale on May 19th, bulk sale to bot:

https://backpack.tf/profiles/76561198980693043#!/compare/1716076800/1716163200

https://backpack.tf/profiles/76561198850121720#!/compare/1716076800/1716163200

Sale on July 1st, bought off of bot for unknown amount:

https://backpack.tf/profiles/76561198850121720#!/compare/1719705600/1719792000

https://backpack.tf/profiles/76561199597848134#!/compare/1719014400/1719792000

Sale on July 9th, bulk dump to bot:

https://backpack.tf/profiles/76561199597848134#!/compare/1719792000/1720483200

https://backpack.tf/profiles/76561198378207723#!/compare/1720483200/1720569600

Second sale on July 9th, dumped to a second bot, doesn't show in either compare:

https://backpack.tf/profiles/76561198378207723#!/compare/1720483200/1720569600

https://backpack.tf/profiles/76561199072654974#!/compare/1720483200/1720656000

Item 3:

Sold on May 9th for $79.90, barely in date:

https://marketplace.tf/items/tf2/30369;5;u61

Can't see all the way back but key price was stable at the time at $1.65 that week: https://marketplace.tf/items/tf2/5021;6

$79.90/1.65=48.42, rounding down to 48. If the value of the keys had changed marginally in either direction, the rounding would be about the same so it should be fine.

Taking 48 keys