Using last month.

Sales 1 & 2:

Sold for $17, $15.99 and $8.10 on marketplace.tf

https://marketplace.tf/items/30673;5;u3004

$8.10 would’ve gone to a buy order, excluding.

17/1.98 = ~8.59

15.99/1.98 = ~8.08

X = 8.5

X = 8

Sale 3:

Sold for 5 keys + 26 ref

Seller: https://backpack.tf/profiles/76561198305676157#!/compare/1525392000/1525478400

Buyer: https://backpack.tf/profiles/76561198204810208#!/compare/1525392000/1525478400

Bot.tf confirms: https://i.imgur.com/AaGdj7d.png

X = 6

Sale 4:

Sold for 5 keys + 26 ref

Seller: https://backpack.tf/profiles/76561198305676157#!/compare/1527465600/1527552000

Buyer: https://backpack.tf/profiles/76561198151693817#!/compare/1527465600/1527552000

Bot.tf confirms: https://i.imgur.com/AaGdj7d.png

X = 6

Sale 5:

Sold for 6 keys

Seller: https://backpack.tf/profiles/76561198048851745#!/compare/1525305600/1525392000

Buyer: https://backpack.tf/profiles/76561198274416961#!/compare/1525392000/1525651200

X = 6

Sale 6:

Sold for 6 keys?

Seller: https://backpack.tf/profiles/76561198274416961#!/compare/1525651200/1525737600

Buyer: https://backpack.tf/profiles/76561198001044586#!/compare/1525651200/1525737600

2 of the keys on the buyer’s end went to a mannco.trade bot, but I believe that those two went to the seller, then the seller deposited those keys to the site, as the key that leaves the seller’s backpack also went to a mannco.trade bot.

X = 6

Sale 7:

Sold to a bot for 5 keys + 3 ref

Seller: https://backpack.tf/profiles/76561198131478921#!/compare/1527465600/1527552000

Buyer: https://backpack.tf/profiles/76561198305676157#!/compare/1527465600/1527552000

Bot.tf confirms: https://i.imgur.com/AaGdj7d.png

X = 5

Sale 8:

Sold to a bot for 5 keys + 3 ref

Seller: https://backpack.tf/profiles/76561198278025376#!/compare/1524960000/1525132800

Buyer: https://backpack.tf/profiles/76561198305676157#!/compare/1525046400/1525132800

Bot.tf confirms: https://i.imgur.com/AaGdj7d.png

X = 5

Sale 9:

Sold for literal trash

Seller: https://backpack.tf/profiles/76561198407321851#!/compare/1525737600/1525996800

Buyer: https://backpack.tf/profiles/76561198397840977#!/compare/1525737600/1525824000

Sale 10:

Bulk for Burning Broadband

Seller: https://backpack.tf/profiles/76561198087462179#!/compare/1526947200/1527379200

Buyer: https://backpack.tf/profiles/76561198079578383#!/compare/1526860800/1526947200

Sale 11:

Bulk for Death at Dusk Gibus

Seller: https://backpack.tf/profiles/76561198317608743#!/compare/1527465600/1527552000

Buyer: https://backpack.tf/profiles/76561198061489334#!/compare/1527465600/1527552000

Sellers:

7 keys:

https://i.imgur.com/GgWvsu5.png

https://backpack.tf/item/4285039983

https://backpack.tf/item/4258195674

https://backpack.tf/item/6110690644

https://backpack.tf/item/5397358345

8 keys:

https://i.imgur.com/FNwyTP9.png

https://backpack.tf/item/4267910770

https://backpack.tf/item/5362911282

10 keys:

https://i.imgur.com/DZqno0b.png

https://backpack.tf/item/6705027430

https://backpack.tf/item/5795242186

11 keys:

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

https://backpack.tf/item/5858230463

https://backpack.tf/item/4257335740

Sales at:

5 (2x)

6 (4x)

8

8.5

5 doesn’t seem too common, excluding 5.

8 and 8.5 seem to high given the cheaper sellers. Excluding 8 and 8.5.

Going with 6 flat.