Sales from previous suggestion still in-date:

Item 1

https://backpack.tf/item/2034163676

Sale #1

Sold for a Circling TF Logo Exquisite Rack (340 keys) + 360 keys (ID "13999451716" of the unusual matches, 363 keys show up in the buyer's but not sure if all of them match histories or not) = 700ish keys-

Seller: https://backpack.tf/profiles/76561198827489734#!/compare/1704067200/1704153600

Buyer: https://backpack.tf/profiles/76561198058356352#!/compare/1704067200/1704153600

MP.TF Sale #1

Sold for $1100 on December 16, 2023

Average Key Price @ $1.73ish

1100/1.73 = 635.83ish keys

https://backpack.tf/item/2034163676

https://marketplace.tf/items/tf2/30030;5;u74

Sales @ 636, 700

New sales:

https://backpack.tf/item/2034163676

https://backpack.tf/profiles/76561198058356352#!/compare/1707696000/1707782400

https://backpack.tf/profiles/76561198171082595#!/compare/1707696000/1707782400

750 keys

https://marketplace.tf/items/tf2/30030;5;u74

https://backpack.tf/item/2050531096

$1100/1.67 = ~659 keys

Sales:

636

659

700

750

Rounding to 640 - 750 keys.