Using sales from this year.

Marketplace Sales:

https://marketplace.tf/items/30673;5;u3010

https://manic.tf/keyprice/?at=2019-02-13 - $8.50 / $1.79 = ~4.748 keys (without rounding)

https://manic.tf/keyprice/?at=2019-02-13 - $9 / $1.79 = 5.03 keys

https://manic.tf/keyprice/?at=2019-01-09 - $10.19 / $1.75 = 5.82 keys

X = 6

X = 5

X = 4.5

Other Sales:

https://backpack.tf/item/7522854121 (#1)

https://backpack.tf/item/7144197473 (#2-4)

https://backpack.tf/item/5371748617 (#5)

https://backpack.tf/item/4256956951 (#6)

https://backpack.tf/item/4256876151 (#7 & #8)

https://backpack.tf/item/7214229819 (#9)

https://backpack.tf/item/4981844474 (#10)

https://backpack.tf/item/4507238484 - scrap, probably not unusual at the time

https://backpack.tf/item/6496549645 - scrap

https://backpack.tf/item/4289808375 - marketplace

https://backpack.tf/item/5661233893 - …unusable

#1

Untraceable

https://backpack.tf/profiles/76561198869298267#!/compare/1549843200/1549929600

https://backpack.tf/profiles/76561198340634356#!/compare/1549843200/1549929600

https://i.imgur.com/9xTW1Bx.png - Labelled as a 3 key + 20 ref purchase

#2

Untraceable

https://backpack.tf/profiles/76561198144945119#!/compare/1548979200/1549065600

https://backpack.tf/profiles/76561198034732229#!/compare/1549065600/1549152000

#3

Sold for cheap items

https://backpack.tf/profiles/76561198341361827#!/compare/1547251200/1547337600

https://backpack.tf/profiles/76561198826621853#!/compare/1547251200/1547337600

#4

Bulk for Strange Haunted Ghosts Air Dog

https://backpack.tf/profiles/76561198826621853#!/compare/1547769600/1547856000

https://backpack.tf/profiles/76561198144945119#!/compare/1547769600/1547856000

#5

Untraceable

https://backpack.tf/profiles/76561198099780165#!/compare/1549584000/1549929600

https://backpack.tf/profiles/76561198079155814#!/compare/1549843200/1549929600

#6

Bulk for Cloud 9 BoA

https://backpack.tf/profiles/76561198132072336#!/compare/1548028800/1548115200

https://backpack.tf/profiles/76561197994697258#!/compare/1548028800/1548115200

#7

Untraceable

https://backpack.tf/profiles/76561198156312632#!/compare/1549843200/1550188800

https://backpack.tf/profiles/76561198108905664#!/compare/1549929600/1550016000

#8

Untraceable

https://backpack.tf/profiles/76561198108905664#!/compare/1550102400/1550188800

https://backpack.tf/profiles/76561198142697531#!/compare/1546214400/1550275200

#9

Untraceable

https://backpack.tf/profiles/76561198334598690#!/compare/1546387200/1546473600

https://backpack.tf/profiles/76561198118577066#!/compare/1491177600/1546473600

https://i.imgur.com/9xTW1Bx.png - labelled as 5 keys

On top of that, the history shows it going to the bot directly from scrap, meaning there’s a missing person in the history making that purchase untraceable also.

#10

SCM

https://backpack.tf/profiles/76561198106786180#!/compare/1546473600/1549411200

https://backpack.tf/profiles/76561198049851804#!/compare/1546300800/1547424000

Sellers:

https://i.imgur.com/9YlZVWr.png

https://backpack.tf/item/4519222751 - 5 keys

https://backpack.tf/item/7522854121 - 5 keys

https://backpack.tf/item/4255551633 - 5 keys

https://backpack.tf/item/6086477286 - 8 keys

Sales at:

4.5

5

6

Additionally, the purchase on bot.tf that occurred 30th December is also untraceable

https://backpack.tf/profiles/76561198345447093#!/compare/1545350400/1546128000

https://backpack.tf/profiles/76561198335791307#!/compare/1546128000/1548720000

https://i.imgur.com/9xTW1Bx.png

If it weren’t, I would’ve included 3.5 in the range.

6 is too high given current sellers. Excluding 6.

Going with 4.5-5.