Using last month, except for sale 2 (reasoning at the bottom)

Sale 1:

Sold for $10.65 on marketplace.tf (sep 8)

https://marketplace.tf/items/30876;5;u3001

https://backpack.tf/item/6378201936 - No outpost

http://manic.tf/keyprice/?at=2018-09-08 - $10.65 / $1.88 = 5.66 keys

X = 5.5

Sale 2:

Sold to a bot for 4 keys + 6.11 ref (Buyer’s end

Seller: https://backpack.tf/profiles/76561198066223704#!/compare/1532736000/1533081600

Buyer: https://backpack.tf/profiles/76561198305676157#!/compare/1532995200/1533081600

https://backpack.tf/item/6252743132

X = 4

Other Sales:

https://backpack.tf/item/6943105564 (#1)

https://backpack.tf/item/6285899007 (#2)

https://backpack.tf/item/6263216272 (#3)

https://backpack.tf/item/6252753186 (#4)

https://backpack.tf/item/6252740514 (#5)

https://backpack.tf/item/6875233295 (#6 & #7)

https://backpack.tf/item/6750514452 - SCM

#1

Sold for ’72 Second Rate Sorcery

https://backpack.tf/profiles/76561198080251323#!/compare/1536278400/1536364800

https://backpack.tf/profiles/76561198127045035#!/compare/1535846400/1536278400

Can be used on the Sorcery.

#2

Untraceable

https://backpack.tf/profiles/76561198092075869#!/compare/1535241600/1535328000

https://backpack.tf/profiles/76561198334598690#!/compare/1535241600/1535328000

https://i.imgur.com/sGSavKZ.png - Labelled as 4 keys and 6.11 ref, but 11 ref matches.

#3

https://backpack.tf/item/6263216272 - scammer

https://i.imgur.com/sGSavKZ.png - labelled as 4 keys + 6.11 ref

#4

Sold for less than the price of a non-unusual copy of this taunt.

https://backpack.tf/profiles/76561198126202789#!/compare/1535328000/1535500800

https://backpack.tf/profiles/76561198112441485#!/compare/1533686400/1536192000

#5

SCM

https://backpack.tf/profiles/76561198221421076#!/compare/1535155200/1535500800

https://backpack.tf/profiles/76561198312685638#!/compare/1535068800/1535241600

#6

Untraceable

https://backpack.tf/profiles/76561198060212574#!/compare/1536796800/1536883200

https://backpack.tf/profiles/76561198820728761#!/compare/1536537600/1536883200

#7

Untraceable

https://backpack.tf/profiles/76561198110534225#!/compare/1536969600/1537142400

https://backpack.tf/profiles/76561198054198170#!/compare/1536796800/1536969600

The bot.tf purchase at 4 keys + 10.77 ref is untraceable to the point where the item’s history can’t be obtained here.

https://bot.tf/stats/item?def=30876&q=5&ef=Showstopper&craft=1&aus=0&ks=0

https://backpack.tf/profiles/76561198295122993#!/compare/1535414400/1535500800

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

Sellers:

https://i.imgur.com/C6MVWoK.png

https://backpack.tf/item/6479895240 - ~5.41 keys

https://backpack.tf/item/6263216272 - 6 keys

https://backpack.tf/item/6285899007 - 6 keys

https://backpack.tf/item/6333664271 - 6 keys

https://backpack.tf/item/6632515650 - 7 keys

Sales at:

4

5.5

The reason I included a sale from early August for the low-end is due to the amount of sales to bot.tf bots at ~4 keys being too large to be ignored, even if all 3 from this month are untraceable.

Similar situation here: https://backpack.tf/suggestion/5b765dbdcf6c751849519243

Going with 4-5.5.