Sales 1-6:

Sold for $14.99, $14.39, $13.50, $13.39, $13 & $8.25

https://marketplace.tf/items/1108;5;u3004

14.99/1.96 = ~7.65

14.39/1.98 = ~7.27

13.5/1.97 = ~6.85

13.39/1.97 = ~6.8

13/1.97 = ~6.6

8.25/1.97 = ~4.19

X = 7.5 (2x)

X = 7 (2x)

X = 6.5

X = 4

Sale 7:

Sold for 5 keys + 14 ref

Seller: https://backpack.tf/profiles/76561198305676157#!/compare/1527206400/1527292800

Buyer: https://backpack.tf/profiles/76561198385375965#!/compare/1527120000/1527292800

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

X = 5.5

Sale 8:

Sold for 5 keys + 14 ref

Seller: https://backpack.tf/profiles/76561198305676157#!/compare/1526860800/1526947200

Buyer: https://backpack.tf/profiles/76561198026736504#!/compare/1526774400/1526947200

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

X = 5.5

Sale 9:

Sold for 5 keys + 12 ref

Seller: https://backpack.tf/profiles/76561198097271466#!/compare/1525737600/1525824000

Buyer: https://backpack.tf/profiles/76561198376903915#!/compare/1525651200/1526774400

X = 5.5

Sale 10:

Sold for 5 keys + 5 ref

Seller: https://backpack.tf/profiles/76561198830746853#!/compare/1526860800/1526947200

Buyer: https://backpack.tf/profiles/76561198420927112#!/compare/1526947200/1527033600

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

X = 5

Sale 11:

Sold for 5 keys + 4 ref

Seller: https://backpack.tf/profiles/76561198420927112#!/compare/1527292800/1527379200

Buyer: https://backpack.tf/profiles/76561198385375965#!/compare/1527292800/1527379200

X = 5

Sale 12:

Sold to a bot for 4 keys + 11.11 ref

Seller: https://backpack.tf/profiles/76561198385965320#!/compare/1526083200/1527292800

Buyer: https://backpack.tf/profiles/76561198305676157#!/compare/1527206400/1527292800

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

X = 4.5

Sale 13:

Sold to a bot for 4 keys + 20 ref

https://backpack.tf/item/6230618687 - Can’t trace seller

Buyer: https://backpack.tf/profiles/76561198305676157#!/compare/1525564800/1525651200

X = 4.5

Sale 14:

Sold for 4 keys

Seller: https://backpack.tf/profiles/76561198173340103#!/compare/1525651200/1525737600

Buyer: https://backpack.tf/profiles/76561198097271466#!/compare/1525564800/1525651200

X = 4

Sale 15:

Bulk for Strange Pro. KS Knife

Seller: https://backpack.tf/profiles/76561198152006793#!/compare/1525651200/1527552000

Buyer: https://backpack.tf/profiles/76561198173340103#!/compare/1525564800/1525651200

Sale 16:

Bulk for Purple Energy Tower

Seller: https://backpack.tf/profiles/76561198150905111#!/compare/1525910400/1525996800

Buyer: https://backpack.tf/profiles/76561198232041512#!/compare/1525910400/1525996800

Sellers:

8 keys:

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

https://backpack.tf/item/4370062009

9 keys:

https://i.imgur.com/WraM9gr.png

https://backpack.tf/item/6270994197

https://backpack.tf/item/3883655649

https://backpack.tf/item/2891088648

11 keys:

https://i.imgur.com/s6HOAz7.png

https://backpack.tf/item/6410349578

Sales at:

4 (2x)

4.5 (2x)

5 (2x)

5.5 (3x)

6.5

7 (2x)

7.5 (2x)

4 seems a little low, excluding.

For the sake of not having a hideous range, I’m gonna shave off the lowest and highest end. Excluding 4.5 and 7.5.

Going with 5-7.