Using last month

Sales 1 & 2:

Sold for $13.89 and $11.90 on Marketplace.tf

https://marketplace.tf/items/1119;5;u3008

13.89/1.97 = ~7.05

11.9/1.97 = ~6.04

X = 7

X = 6

Sale 3:

Sold for 5 keys?

Seller: https://backpack.tf/profiles/76561198086076383#!/compare/1521936000/1522022400

Buyer: https://backpack.tf/profiles/76561198041621614#!/compare/1521849600/1522022400

https://backpack.tf/item/6264077260 - Item history shows it came from a sfuminator bot, I’d guess it was pulled from the bot, or sold to the bot and the keys were withdrawn immediately after the trade. I don’t use sfuminator, so I don’t know how it works.

https://i.imgur.com/NeOtYAM.png - Bot.tf shows 3 sales at 5 keys, this may be one of them.

X = 5

Sale 4:

Sold for 5 keys

Seller: https://backpack.tf/profiles/76561198386441509#!/compare/1522886400/1522972800

Buyer: https://backpack.tf/profiles/76561198253471602#!/compare/1522886400/1522972800

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

X = 5

Sale 5:

Another bot.tf sales at 5 keys (assuming sale 3 IS a bot.tf sale)

https://backpack.tf/profiles/76561198308819102#!/compare/1522627200/1522713600

https://backpack.tf/profiles/76561198086295734#!/compare/1518393600/1522713600

Might be this sale, untraceable though.

X = 5

Sale 6:

Sold for 4 keys + some metal

Seller: https://backpack.tf/profiles/76561198121830870#!/compare/1522800000/1522886400

Buyer: https://backpack.tf/profiles/76561198125035818#!/compare/1522713600/1522886400

I don’t think all the metal that was involved shows in this trade, and if this sale ends up being 4.5 keys, it’ll be too low.

Sale 7:

Sold for Steaming Carouser’s Capotain

Seller: https://backpack.tf/profiles/76561198398063696#!/compare/1523836800/1524355200

Buyer: https://backpack.tf/profiles/76561198254410537#!/compare/1524268800/1524355200

This is gonna be an outlier, excluding.

Sellers:

~5.07 keys:

https://i.imgur.com/vXn9TP8.png

https://backpack.tf/item/6348739066

~5.18 keys:

https://i.imgur.com/amJPv4k.png

https://backpack.tf/item/2963362534

~5.87 keys:

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

https://backpack.tf/item/5580298209

7 keys:

http://www.tf2outpost.com/trade/29610335

~11.5 keys:

https://i.imgur.com/8jJLUYa.png

https://backpack.tf/item/4614206508

15 keys:

http://www.tf2outpost.com/trade/29185629

20 keys:

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

https://backpack.tf/item/2828141887

Sales at:

5 (3x)

6

7

Calling 6 and 7 outliers, given the month-old seller at ~5.87 keys.

Going with 5 flat.