Sale 1:

Sold for 6 keys

https://backpack.tf/profiles/76561199203180827#!/compare/1721952000/1722038400 - Near ID: 14716174959

https://backpack.tf/profiles/76561198041618568#!/compare/1721952000/1722038400

https://backpack.tf/item/13908501369

= 6 keys

Sale 2:

Sold for 6 keys

https://backpack.tf/profiles/76561199059160806#!/compare/1722038400/1722124800 - Near ID: 14722280676

https://backpack.tf/profiles/76561198204348819#!/compare/1722038400/1722124800

https://backpack.tf/item/6491269099

= 6 keys

Sale 3:

Sold for 6 keys

https://backpack.tf/profiles/76561199059160806#!/compare/1724630400/1724716800 - Near ID: 14841323824

https://backpack.tf/profiles/76561198055923827#!/compare/1724716800/1724803200

https://backpack.tf/item/6479216578

= 6 keys

Sale 4:

Sold to a bot for 3 keys + 25 ref (~0.45 keys at the time)

https://backpack.tf/profiles/76561198211033277#!/compare/1724544000/1724630400

https://backpack.tf/profiles/76561199059160806#!/compare/1724457600/1724544000

https://backpack.tf/item/6479216578

= 3.45 keys

Sale 5:

Sold to a bot for 3 keys

https://backpack.tf/profiles/76561198066569256#!/compare/1721952000/1722124800

https://backpack.tf/profiles/76561199059160806#!/compare/1722038400/1722124800

https://backpack.tf/item/6491269099

= 3 keys

Other Sales:

#1

https://backpack.tf/profiles/76561198400372589#!/compare/1723161600/1723248000

https://backpack.tf/profiles/76561198129739068#!/compare/1723161600/1723248000

https://backpack.tf/item/14742618018

Untraceable

#2

https://backpack.tf/profiles/76561198129739068#!/compare/1723334400/1723420800

https://backpack.tf/profiles/76561198034615270#!/compare/1723334400/1723420800

https://backpack.tf/item/14742618018

Bulk for keys

#3 & 4

https://backpack.tf/profiles/76561198850178158#!/compare/1721952000/1722038400

https://backpack.tf/profiles/76561199076018223#!/compare/1721952000/1722038400

https://backpack.tf/profiles/76561199203180827#!/compare/1721952000/1722038400

Nothing traceable here, moved too fast and nothing matches

#5

https://backpack.tf/profiles/76561198027785685#!/compare/1722297600/1722384000

https://backpack.tf/profiles/76561198035664616#!/compare/1722297600/1722384000

https://backpack.tf/item/6674527906

Bulk

#6

https://backpack.tf/profiles/76561198055923827#!/compare/1724803200/1724889600

https://backpack.tf/profiles/76561198846756785#!/compare/1724716800/1724889600

https://backpack.tf/item/6479216578

Bulk for Orbiting Fire Nuke

https://backpack.tf/item/11947350429 - unusualified

https://backpack.tf/item/11131947438 - unusualified

https://backpack.tf/item/11015190744 - unusualified

https://backpack.tf/item/9543193950 - unusualified

https://backpack.tf/item/9500130890 - unusualified

https://backpack.tf/item/6778855340 - unusualified

https://backpack.tf/item/6480264491 - unusualified

Sellers:

https://i.imgur.com/AmGuD9k.png

https://backpack.tf/item/11947350429 - 32 keys

https://backpack.tf/item/6479216578 - 35 keys

https://backpack.tf/item/14742618018 - 35 keys

Sales at:

3

3.45

6 (3x)

It could be argued that at least 3.45 keys should be included in the range, but given how quickly the sales at 6 occurred (all took 1-3 days to sell), I feel that it would be best to exclude the sales to bots at 3 and 3.45.

Taking 6 flat.