Sales 1-4:

Sold for $14.68, $14.39, $14.99, & $15 on marketplace.tf

https://marketplace.tf/items/30763;5;u3003

https://manic.tf/keyprice/?at=2018-09-22 - $14.68 / $1.84 = 7.98 keys

https://manic.tf/keyprice/?at=2018-09-29 - $14.39 / $1.84 = 7.82 keys

https://manic.tf/keyprice/?at=2018-10-05 - $14.99 / $1.8 = 8.33 keys

https://manic.tf/keyprice/?at=2018-10-12 - $15 / $1.78 = 8.43 keys

X= 8.5 (2x)

X = 8 (2x)

Sale 5:

Sold for 8 keys

Seller: https://backpack.tf/profiles/76561198334598690#!/compare/1537747200/1537833600

Buyer: https://backpack.tf/profiles/76561198190084707#!/compare/1537747200/1537833600

https://backpack.tf/item/5453602693

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

X = 8

Sale 6:

Sold for 7 keys + 26 ref

Seller: https://backpack.tf/profiles/76561198312583107#!/compare/1538956800/1539043200

Buyer: https://backpack.tf/profiles/76561198309100349#!/compare/1539043200/1539129600

https://backpack.tf/item/7050271020

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

X = 7.5

Sale 7:

Sold to a quickbuyer for 7 keys

Seller: https://backpack.tf/profiles/76561198449971317#!/compare/1537056000/1537142400

Buyer: https://backpack.tf/profiles/76561198397249586#!/compare/1537056000/1537142400

https://backpack.tf/item/5394781860

X = 7

Other Sales:

https://backpack.tf/item/7050271020 (#1)

https://backpack.tf/item/6926228539 (#2)

https://backpack.tf/item/5874521731 (#3)

https://backpack.tf/item/5735625099 (#4)

https://backpack.tf/item/6491862507 - untraceable, seller hasn’t updated backpack since trading, buyer’s backpack wasn’t scanned prior to the sale

https://backpack.tf/item/6705179946 - bots

https://backpack.tf/item/5742032406 - marketplace

https://backpack.tf/item/5382417115 - marketplace

https://backpack.tf/item/5374895818 - marketplace

https://backpack.tf/item/5584972500 - not unusual at the time

#1

Untraceable, only 3 keys match. Dumped on scrap afterwards.

https://backpack.tf/profiles/76561198309100349#!/compare/1539129600/1539216000

https://backpack.tf/profiles/76561198151599525#!/compare/1539043200/1539216000

#2

Untraceable

https://backpack.tf/profiles/76561198151161624#!/compare/1537833600/1538006400

https://backpack.tf/profiles/76561198058259594#!/compare/1537833600/1537920000

#3

Bulk for Beams Sola Topi

https://backpack.tf/profiles/76561198044547547#!/compare/1537056000/1537142400

https://backpack.tf/profiles/76561198855485521#!/compare/1536969600/1537142400

#4

Untraceable

https://backpack.tf/profiles/76561198363395191#!/compare/1537574400/1537660800

https://backpack.tf/profiles/76561198128213644#!/compare/1539043200/1539216000

Probably bought from the bot then gambled

Sellers:

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

https://backpack.tf/item/5230851110 - 9 keys

https://backpack.tf/item/4959494173 - 12 keys

https://backpack.tf/item/6976037965 - 15 keys

https://backpack.tf/item/4953002735 - 16 keys

Sales at:

7

7.5

8 (3x)

8.5 (2x)

7 is a single sale to a quickbuyer, excluding 7.

Going with 7.5-8.5