Using last 2 months.

Sale 1:

Sold for 5 keys + 29 ref (~5.5 keys)

https://backpack.tf/profiles/76561199043177646#!/compare/1708473600/1708560000

https://backpack.tf/profiles/76561198084024877#!/compare/1707696000/1709251200

https://backpack.tf/item/12660183515

= 5.5 keys

Sale 2:

Sold for 5 keys

https://backpack.tf/profiles/76561198859721638#!/compare/1708819200/1708905600

https://backpack.tf/profiles/76561198384547381#!/compare/1708905600/1709510400

https://backpack.tf/item/11628776833

= 5 keys

Sale 3:

Sold to a bot for 4 keys + 12.11 ref (~0.2 keys)

https://backpack.tf/profiles/76561198143715421#!/compare/1708387200/1708473600

https://backpack.tf/profiles/76561199043177646#!/compare/1708387200/1708473600

https://backpack.tf/item/12660183515

https://backpack.tf/item/12961038431

https://backpack.tf/item/13144335622

https://backpack.tf/item/13686686674

https://backpack.tf/item/13689028901 - 4 keys

https://backpack.tf/item/13795827653

https://backpack.tf/item/14172132232

https://backpack.tf/item/14159578997

https://backpack.tf/item/14172084308

https://backpack.tf/item/12311763390

https://backpack.tf/item/14120198798

https://backpack.tf/item/14186217720

https://backpack.tf/item/13462851411

https://backpack.tf/item/14125528852

https://backpack.tf/item/12910253753

https://backpack.tf/item/14118050232

https://backpack.tf/item/14069127309 - 12 ref

https://backpack.tf/item/14158562101 - 1 scrap

I had the key and metal histories saved because when I saw this sale, it was at the start of the day, so I knew it was gonna be untraceable otherwise if I didn't track every item's history.

= 4.2 keys

Other Sales:

#1

https://backpack.tf/profiles/76561198135388328#!/compare/1702771200/1702857600

https://backpack.tf/profiles/76561198861644611#!/compare/1702684800/1703203200

https://backpack.tf/item/13543442183

Sold with Midnight Whirlwind Yeti Punch for 8keys

#2

https://backpack.tf/profiles/76561198861644611#!/compare/1703203200/1703548800

https://backpack.tf/profiles/76561198135388328#!/compare/1703203200/1703289600

https://backpack.tf/item/13543442183

Bulk/Untraceable

#3

https://backpack.tf/profiles/76561198098579571#!/compare/1704499200/1704844800

https://backpack.tf/profiles/76561198841279602#!/compare/1704758400/1704844800

https://backpack.tf/item/13143768805

Untraceable, 3 keys + some metal match

https://imgur.com/a/hkCMfRK - Buy order was ~4.25 keys at the time

#4

https://backpack.tf/profiles/76561198045674946#!/compare/1701820800/1701907200

https://backpack.tf/profiles/76561197980575212#!/compare/1701475200/1701907200

https://backpack.tf/item/12660183515

Untraceable

#5

https://backpack.tf/profiles/76561197980575212#!/compare/1701475200/1701907200

https://backpack.tf/profiles/76561198044852450#!/compare/1701820800/1701907200

https://backpack.tf/item/12660183515

Untraceable/Bulk

#6

https://backpack.tf/profiles/76561198044852450#!/compare/1701820800/1701907200

https://backpack.tf/profiles/76561198262737873#!/compare/1701907200/1701993600

https://backpack.tf/item/12660183515

Untraceable

#7

https://backpack.tf/profiles/76561198262737873#!/compare/1701907200/1701993600

https://backpack.tf/profiles/76561198338285317#!/compare/1701216000/1701993600

https://backpack.tf/item/12660183515

Bulk/Gambled. The entire history here could've just been gambling.

#8

https://backpack.tf/profiles/76561198986780642#!/compare/1707436800/1707609600

https://backpack.tf/profiles/76561199315621199#!/compare/1707436800/1707523200

https://backpack.tf/item/14120831214

Untraceable

#9

https://backpack.tf/profiles/76561199059800460#!/compare/1707696000/1707782400

https://backpack.tf/profiles/76561198017911471#!/compare/1707696000/1707782400

https://backpack.tf/item/9538273882

Untraceable

#10

https://backpack.tf/profiles/76561198017911471#!/compare/1707782400/1707868800

https://backpack.tf/profiles/76561199026390261#!/compare/1707696000/1707782400

https://backpack.tf/item/9538273882

Untraceable

#11

https://backpack.tf/profiles/76561198858123940#!/compare/1708387200/1708473600

https://backpack.tf/profiles/76561199306781068#!/compare/1708300800/1708387200

https://backpack.tf/item/12660183515

cs.trade. untraceable same for the one afterwards.

#12

https://backpack.tf/profiles/76561198135388328#!/compare/1708041600/1708128000

https://backpack.tf/profiles/76561199380063324#!/compare/1707955200/1708128000

https://backpack.tf/item/9566402341

Untraceable

#13

https://backpack.tf/profiles/76561198066567681#!/compare/1708041600/1709337600

https://backpack.tf/profiles/76561199183171982#!/compare/1708646400/1708732800

https://backpack.tf/item/10321227486

Backpack buy

https://backpack.tf/item/11995967277 - marketplace

https://backpack.tf/item/9539087947 - gambled

https://backpack.tf/item/9538273882 - scammer

Sellers:

https://imgur.com/a/fE5cjcd

https://backpack.tf/item/13143768805 - ~7.5 keys

https://backpack.tf/item/9889079345 - marketplace

https://backpack.tf/item/10321227486 - marketplace

https://backpack.tf/item/9587197621 - marketplace

https://backpack.tf/item/11995967277 - marketplace

https://backpack.tf/item/11009644254 - marketplace

https://backpack.tf/item/12675441332 - marketplace

Sales at:

4.2

5

5.5

Buyers up to ~4.35 keys, excluding 4.2.

Taking 5-5.5 keys.