Using last month.

Sale 1:

Sold for 4 keys

Seller: https://backpack.tf/profiles/76561198132741569#!/compare/1548806400/1548892800

Buyer: https://backpack.tf/profiles/76561198142669999#!/compare/1548892800/1548979200

https://backpack.tf/item/7353469268

X = 4

Sale 2:

Sold for 4 keys

Seller: https://backpack.tf/profiles/76561198011321852#!/compare/1548892800/1548979200

Buyer: https://backpack.tf/profiles/76561198027603870#!/compare/1548892800/1548979200

https://backpack.tf/item/6556200070

X = 4

Sale 3:

Sold for 4 keys

Seller: https://backpack.tf/profiles/76561198135471147#!/compare/1547856000/1548028800

Buyer: https://backpack.tf/profiles/76561198084113284#!/compare/1547942400/1548028800

https://backpack.tf/item/4678441880

X = 4

Sale 4:

Sold for 3 keys + 25 ref

Seller: https://backpack.tf/profiles/76561198057413615#!/compare/1549670400/1549843200

Buyer: https://backpack.tf/profiles/76561198352514459#!/compare/1549497600/1549756800

https://backpack.tf/item/3186450540

X = 3.5

Other Sales:

https://backpack.tf/item/7353469268 (#1 & #2)

https://backpack.tf/item/6687132018 (#3)

https://backpack.tf/item/6564800304 (#4)

https://backpack.tf/item/6464043999 (#5)

https://backpack.tf/item/2689818438 (#6)

https://backpack.tf/item/2689818438 (#7)

https://backpack.tf/item/3344459109 - gambled

https://backpack.tf/item/5389989555 - tf2mart/scrap

https://backpack.tf/item/4633773186 - mannco

https://backpack.tf/item/2775147350 - mannco

https://backpack.tf/item/2759523132 - mannco

https://backpack.tf/item/4556559083 - scrap

https://backpack.tf/item/2700990820 - scrap

https://backpack.tf/item/2760610036 - scrap (this and the last one are most likely missing a person in the history, that bought from scrap and instantly resold to the bots before their backpack was scanned. Both purchases appear as 3 keys + 20 ref on bot.tf https://i.imgur.com/0NQzAvq.png )

#1

Untraceable, probably gambled

https://backpack.tf/profiles/76561198223432116#!/compare/1547942400/1548115200

https://backpack.tf/profiles/76561198321443975#!/compare/1548028800/1548115200

#2

Bulk on both ends

https://backpack.tf/profiles/76561198321443975#!/compare/1548806400/1548892800

https://backpack.tf/profiles/76561198132741569#!/compare/1548720000/1548806400

#3

Untraceable

https://backpack.tf/profiles/76561198023051867#!/compare/1549152000/1549238400

https://backpack.tf/profiles/76561198068911025#!/compare/1548979200/1549324800

#4

SCM

https://backpack.tf/profiles/76561198363395191#!/compare/1547683200/1547769600

https://backpack.tf/profiles/76561198281867235#!/compare/1548547200/1549238400

#5

Sold for a key + 85+ vintage huntsmans

https://backpack.tf/profiles/76561198332869276#!/compare/1549497600/1549584000

https://backpack.tf/profiles/76561198137804582#!/compare/1549497600/1549670400

a sale like this shouldn’t be used here lol

#6

Untraceable

https://backpack.tf/profiles/76561198363395191#!/compare/1548201600/1548288000

https://backpack.tf/profiles/76561198330969028#!/compare/1548201600/1548288000

#7

Untraceable

https://backpack.tf/profiles/76561198330969028#!/compare/1549065600/1549152000

https://backpack.tf/profiles/76561198340634356#!/compare/1548979200/1549065600

https://i.imgur.com/0NQzAvq.png - labelled as 3 keys + 20 ref on bot.tf

Sellers:

https://i.imgur.com/DHMsrd1.png

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

https://backpack.tf/item/3186450540 - ~3.9 keys

https://backpack.tf/item/4788345881 - 4 keys

https://backpack.tf/item/2689818438 - ~4.1 keys

https://backpack.tf/item/2760610036 - ~4.1 keys

https://backpack.tf/item/7165429984 - ~4.1 keys

https://backpack.tf/item/6464043999 - 5 keys

https://backpack.tf/item/3617214482 - 8 keys

https://backpack.tf/item/2918145297 - 12 keys

https://backpack.tf/item/2964889197 - 12 keys

https://backpack.tf/item/4702427746 - 12 keys

Sales at:

3.5

4 (3x)

https://marketplace.tf/items/1116;5;u3005 - there is a marketplace sale, but it isn’t needed, neither would they be added to the range due to the mass amount of sellers at 4. (the sale ends up around 6 keys or more)

Keeping 3.5. My reasoning being that there’s currently a seller at 3.9, so 4 flat wouldn’t do well, and there are plenty of bot purchases at 3.5, even if they are all untraceable (referring to the bot.tf ones mentioned in the “other sales” section).

Going with 3.5-4.