Using last month.

Sales 1 & 2:

Sold for $25 and $24.99 on marketplace.tf

https://marketplace.tf/items/167;5;u3008

25/1.97 = ~12.7

24.99/1.97 = ~12.7

X = 13 (2x)

Sale 3:

Sold for 9 keys

Seller: https://backpack.tf/profiles/76561198344933095#!/compare/1524787200/1524873600

Bot.tf confirms: https://i.imgur.com/sykz7gI.png

Buyer isn’t traceable. It isn’t the next person in the history because they got it from the SCM:

https://backpack.tf/item/6354988181

https://backpack.tf/profiles/76561198063598007#!/compare/1525132800/1525478400

X = 9

Sale 4:

Sold to a bot for 7 keys

Seller: https://backpack.tf/profiles/76561197997283715#!/compare/1526601600/1526688000

Buyer: https://backpack.tf/profiles/76561198312265776#!/compare/1526601600/1526688000

Bot.tf confirms: https://i.imgur.com/sykz7gI.png

X = 7

Sale 5:

Bulk for Green Confetti Glengarry Bonnet

Seller: https://backpack.tf/profiles/76561198018808160#!/compare/1525651200/1525737600

Buyer: https://backpack.tf/profiles/76561198114800338#!/compare/1525651200/1525737600

Sellers:

~8.7 keys:

https://i.imgur.com/P8dNxcH.png

https://backpack.tf/item/6417789149

11 keys:

https://i.imgur.com/PT5OuHy.png

https://backpack.tf/item/1318841504

12 keys:

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

https://backpack.tf/item/2061033875

50 keys:

http://www.tf2outpost.com/trade/29510504

Sales at:

7

9

13 (2x)

Sales at 13 are outliers, due to the cheaper sellers.

7 seems kinda low, excluding.

Using the unsold at ~8.7 keys as the low-end (8.5)

Going with 8.5-9.