Using last month

Sale 1:

Sold for 15 keys + 18 ref

Seller: https://backpack.tf/profiles/76561198344933095#!/compare/1523059200/1523145600

Buyer: https://backpack.tf/profiles/76561198232157836#!/compare/1523059200/1523145600

Bot.tf confirms: https://i.imgur.com/QY2A19o.png

X = 16

Sale 2:

Sold for $27.02 on Marketplace.tf

https://marketplace.tf/items/1162;5;u3008

Can’t find item’s history

27.02/1.97 = ~13.72

X = 14

Sale 3:

Sold for Killstreak Aus FaN (10)

Seller: https://backpack.tf/profiles/76561198820686501#!/compare/1523318400/1523577600

Buyer: https://backpack.tf/profiles/76561198017911489#!/compare/1523232000/1523318400

X = 10

Sale 4:

Bulk for Insomnia HKC

Seller: https://backpack.tf/profiles/76561198140010255#!/compare/1522540800/1522972800

Buyer: https://backpack.tf/profiles/76561198305458404#!/compare/1522454400/1522972800

Sellers:

55 keys:

https://i.imgur.com/lr7dyHP.png

https://backpack.tf/item/6459338369

SCM: (Taking keys as $2.47)

https://i.imgur.com/KPsUGCB.png (Only the first 4 are relevant here)

$32.29 (~13.1 keys)

$32.73 (~13.1 keys)

$34.42 (~13.9 keys)

$34.93 (~14.1 keys)

Sales at:

10

14

16

Gonna disregard the SCM sellers at ~13 keys, not that far off the low-end, and can’t tell how long they’ve been there for anyways.

https://i.imgur.com/aqyIpiM.png - Quickbuyers at 10+ keys, excluding 10.

Going with 14-16.