Marketplace Sales:

https://marketplace.tf/items/tf2/31157;5;u3007

https://backpack.tf/item/16256676233 - April 1st

https://backpack.tf/item/9723868254 - May 1st

$6.64, April 1st

$6.78, May 1st

https://marketplace.tf/items/tf2/5021;6 - keys were:

$1.97, April 1st

$2, May 1st

6.64/1.97 = 3.371, rounds to 3.35 keys

6.78/2 = 3.39, rounds to 3.4 keys

Other Sales:

#1

https://backpack.tf/profiles/76561198316831771#!/compare/1771977600/1772064000

https://backpack.tf/profiles/76561199564942025#!/compare/1771977600/1772064000

https://backpack.tf/item/9738280725

Untraceable

#2

https://backpack.tf/profiles/76561198093501381#!/compare/1773014400/1774051200

https://backpack.tf/profiles/76561199702175743#!/compare/1773878400/1773964800

https://backpack.tf/item/10732346697

Untraceable

#3

https://backpack.tf/profiles/76561199702175743#!/compare/1777507200/1777593600

https://backpack.tf/profiles/76561198850121720#!/compare/1777507200/1777593600

https://backpack.tf/item/10732346697

Bulk/untraceable

#4

https://backpack.tf/profiles/76561198244801080#!/compare/1775433600/1775779200

https://backpack.tf/profiles/76561198850274253#!/compare/1775347200/1775433600

https://backpack.tf/item/13090205422

Bulk/untraceable

#5

https://backpack.tf/profiles/76561198161137820#!/compare/1775174400/1775260800

https://backpack.tf/profiles/76561198380634252#!/compare/1775174400/1775260800

https://backpack.tf/item/11338430314

Untraceable, skipped past all the gambling in the history.

https://backpack.tf/item/13909098244 - unusualified

https://backpack.tf/item/15340758225 - qsstore

Sellers:

https://i.imgur.com/IWs0FJj.png

https://backpack.tf/item/10732346697 - ~4.55 keys (marketplace seller sold)

https://stntrading.eu/item/tf2/Unusual+Skill+Gotten+Gains+Taunt%3A+Scorcher%27s+Solo

https://backpack.tf/item/9738280725

https://i.imgur.com/vdFvpmk.png - ~3.35 keys

Sales at:

3.35

3.4

Taking 3.35-3.4 keys.