Three recent histories.

Sale 1:

https://backpack.tf/item/7957566016

https://backpack.tf/profiles/76561198188093413#!/compare/1606003200/1606176000

https://backpack.tf/profiles/76561199084784906#!/compare/1606003200/1606089600

Very difficult to trace. Cannot find the item leaving the seller's inventory.

Sale 2:

https://backpack.tf/item/7957566016

https://backpack.tf/profiles/76561199084784906#!/compare/1607126400/1607212800

https://backpack.tf/profiles/76561198139606552#!/compare/1607126400/1607212800

28 keys pure. Only traceable on the seller's end.

Sale 3:

https://backpack.tf/item/7957566016

https://backpack.tf/profiles/76561198139606552#!/compare/1607299200/1607558400

https://backpack.tf/profiles/76561198850121720#!/compare/1607472000/1607558400

Untraceable bot sale.

Sale 4:

https://backpack.tf/item/5458932313

https://backpack.tf/profiles/76561198062916431#!/compare/1600819200/1603843200

https://backpack.tf/profiles/76561198195933333#!/compare/1603756800/1604793600

Very difficult to trace. The seller's inventory is rarely updated.

Sale 5:

https://backpack.tf/item/3584437156

https://backpack.tf/profiles/76561198232016356#!/compare/1603929600/1604016000

https://backpack.tf/profiles/76561198297644819#!/compare/1603929600/1604016000

Bulk for something. This hat + 40 keys + 3 TOD tickets (~1.5 keys). Not using because we don't know what it was for.

Conclusion:

Taking 28 keys. Corresponds with the unsolds at 29-30 keys in the classified listings. https://gyazo.com/3c80f7d6d773286dadceb7ddf21e3c48