Using last month.

Marketplace Sales:

https://marketplace.tf/items/tf2/30671;5;u3010

$5.37, Jul 28th

$8, Jul 8th

https://manic.tf/keyprice/?at=2019-07-08 - $8 / $1.83 = 4.37 keys

https://manic.tf/keyprice/?at=2019-07-28 - $5.37 / $1.8 = 2.98 keys

X = 4.5

X = 3

Other Sales:

https://backpack.tf/item/5259506773 (#1)

https://backpack.tf/item/4739047205 (#2)

https://backpack.tf/item/7889494175 - gambled/scm

https://backpack.tf/item/4745657468 - scrap/marketplace

https://backpack.tf/item/4416389612 - scrap

#1

Untraceable, probably marketplace

https://backpack.tf/profiles/76561198311498888#!/compare/1564099200/1564185600

https://backpack.tf/profiles/76561198052915226#!/compare/1472428800/1564358400

#2

Untraceable

https://backpack.tf/profiles/76561198453417865#!/compare/1564272000/1564358400

https://backpack.tf/profiles/76561198374431966#!/compare/1564272000/1564358400

https://i.imgur.com/cxHjX3y.png - labelled as a 3 key sale

#3

Untraceable

https://backpack.tf/profiles/76561198870144729#!/compare/1561593600/1563321600

https://backpack.tf/profiles/76561198453417865#!/compare/1562630400/1562716800

https://i.imgur.com/cxHjX3y.png - labelled as a 3 key + 15 ref purchase (~3.5 keys)

Sellers:

https://i.imgur.com/0AkhSzX.png

https://backpack.tf/item/6693213230 - ~3.5 keys

https://backpack.tf/item/7747635959 - ~3.9 keys

https://backpack.tf/item/7214878475 - 4 keys

https://backpack.tf/item/4565337963 - 6 keys

Sales at:

3

4.5

4.5 is a large outlier, excluding.

Bot.tf sale at 3 supports. Ignoring the ~3.5 key purchase, as it’s lower than what they re-sold for, and due to the lack of current buyers anywhere near it.

Going with 3 flat.