List of in date sales:

Sellers Inventory: https://backpack.tf/profiles/76561197992711280#!/compare/1672444800/1673222400

Buyers Inventory: https://backpack.tf/profiles/76561198013245606#!/compare/1672358400/1673136000

Private sale so can't find value from this.

Today's purchase of clean DBD antlers for $5,100:

https://imgur.com/a/3WRFHEc

Thank you Shufflespy:

https://backpack.tf/profiles/76561198049469629#!/compare/1678147200/1678233600 - Not good to use because the Whirly owner paid 5200

Even if ultralow was paying $1.75 per Key, he isn't the Key market. In addition to the 1.8/1.81 buyers MisterBoot linked,

https://forums.backpack.tf/topic/82146-buying-%E2%82%AC172-per-tf2-key-%F0%9F%97%9D%EF%B8%8F%F0%9F%97%9D%EF%B8%8F%F0%9F%94%91-paypalrevolutmonesen26zencomicard/ - €1.72 buyer (~$1.83 - 1.84)

https://forums.backpack.tf/topic/66342-buying-keys-for-182-paypal/page/3/ - $1.82 buyer

If we average the Key price from 1.8 - 1.84 = 1.82, then this sale should be 5104.99 / 1.82 = ~2800 Keys

2800 would work here.