Sale 1:

Sold for 8 keys

Seller: https://backpack.tf/profiles/76561198357046243#!/compare/1525824000/1525996800

Buyer: https://backpack.tf/profiles/76561198041108750#!/compare/1525910400/1525996800

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

https://backpack.tf/item/6839042571

https://backpack.tf/item/6839042578

https://backpack.tf/item/6839042585

https://backpack.tf/item/6839042590

https://backpack.tf/item/6839042600

https://backpack.tf/item/6839042607

https://backpack.tf/item/6839042614

https://backpack.tf/item/6839042627

X = 8

Sales 2 & 3:

Sold for $14.99 and $8.25 on Marketplace.tf

https://marketplace.tf/items/30843;5;u3007

https://backpack.tf/item/6768032701

http://www.tf2outpost.com/trade/29615091 - B/O of 7

$8.25 one would’ve gone to a buy order, excluding that one.

X = 7 (Capped by B/O)

Sale 4:

Sold for 6 keys

Seller: https://backpack.tf/profiles/76561198133814282#!/compare/1526083200/1526169600

Buyer: https://backpack.tf/profiles/76561198392385202#!/compare/1521244800/1526169600

X = 6

Sale 5:

Sold for 5 keys + 5 ref

https://i.imgur.com/d0HAiCu.png

Seller: https://backpack.tf/profiles/76561198048851745#!/compare/1525910400/1525996800

Buyer: https://backpack.tf/profiles/76561198250923612#!/compare/1525910400/1525996800

X = 5

Sale 6:

Sold for 4 keys + 20 ref

Seller: https://backpack.tf/profiles/76561198121830870#!/compare/1525305600/1525392000

Buyer: https://backpack.tf/profiles/76561198008720570#!/compare/1525132800/1525392000

X = 4.5

Sellers:

~5.7 keys:

https://i.imgur.com/7yzI5Xo.png

https://backpack.tf/item/6774281366

Offers:

http://www.tf2outpost.com/trade/29628629

Sales at:

4.5

5

6

7

8

Gonna shave off the lowest and highest sales to shorten the range. Excluding 4.5 and 8.

Going with 5-7.