I'm an idiot and forgot to check the steam market last time. Thanks to Paradise, j58, and Offline for their reminders. Still an easy suggestion, only 2 sales.

Sale #1 (Steam Marketplace)

https://steamcommunity.com/market/listings/440/Unusual%20Virus%20Doctor

https://backpack.tf/profiles/76561198101898461#!/compare/1555977600/1556841600

Sold for $235.10

Keys on the Steam Market that day were $2.47

$235.10/$2.47 = 95.1 keys. Rounding to 95.

Sale #2 (Pure Keys)

https://backpack.tf/profiles/76561198062779400#!/compare/1557273600/1557360000

https://backpack.tf/profiles/76561198107246593#!/compare/1557273600/1557360000

75 keys.

Going with 75-95

https://marketplace.tf/items/30043;5;u13

Sold on May 24, 2019 for $90.50

Keys that day were $1.81

https://marketplace.tf/items/5021;6/Mann%20Co.%20Supply%20Crate%20Key

90.50/1.81 = 50 keys.

Clearly a quicksell. Ignoring.