Mmm

SALE 1

sold for 12 keys + 20 refined

https://backpack.tf/profiles/76561198076020691#!/compare/1563494400/1563580800

Rounds down to 12 keys

SALE 2

Bulk for mg ye oiled baker boy

https://backpack.tf/profiles/76561198117971944#!/compare/1562198400/1562544000

SALE 3

Sold for 12 keys + 2 refined

https://backpack.tf/profiles/76561197976392732#!/compare/1562803200/1563062400

Rounds down to 12 keys

SALE 4

Sold for 13 keys

https://backpack.tf/profiles/76561198337734785#!/compare/1563148800/1563235200

https://backpack.tf/profiles/76561198307602421#!/compare/1562803200/1563235200

(All keys match up in second compare link)

SALE 5

sold for 12 keys + 20.11 refined

https://backpack.tf/profiles/76561198069137737#!/compare/1563062400/1563148800

Rounds down to 12 keys

SALE 6

Sold for 12 keys + 8 refined

https://backpack.tf/profiles/76561198153818314#!/compare/1556236800/1556323200

Rounds down to 12 keys

Classifieds at the time of making this suggestion.

https://gyazo.com/a4dc69afc3c8a1e2fccdfebb69676b6f

Sales at 12, 12, 12, 12, and 13. Yes, there are buyers at 12, but there are multiple sales at 12 and shouldn't be excluded as it seems quite common. Taking a range of 12-13 keys here.