New sales:

https://marketplace.tf/items/tf2/30042;5;u61

$29.90 = ~18 keys

https://backpack.tf/item/7956897398

https://backpack.tf/profiles/76561198841279602#!/compare/1714435200/1714521600

https://backpack.tf/profiles/76561198135629317#!/compare/1714521600/1715126400

Looks like it sold for 15? Histories are a bit weird

Creds Erik for the rest:

https://backpack.tf/profiles/76561199026390261#!/compare/1710547200/1710633600

https://backpack.tf/profiles/76561198237025590#!/compare/1709424000/1711065600

https://gyazo.com/ada6ac11abf2abd1f271fbec86f0e0da

STN sale was probably 15.5 but untrace

https://backpack.tf/profiles/76561199026390261#!/compare/1706140800/1706227200

https://backpack.tf/profiles/76561197971490933#!/compare/1706140800/1706227200

Sold along a Bubbling Translator for 27 keys.

Translator:

https://backpack.tf/profiles/76561199238930994#!/compare/1709510400/1709596800

https://backpack.tf/profiles/76561199375529472#!/compare/1706054400/1709510400

Sold for 11 keys + ~0.5 in stuff = ~12.

Making this 27-12 = 15 keys.

13 - 15 will work here. There's enough buy order dumps to support 13's inclusion.