Using last 2 months.

Sale 1:

Sold for 5 keys

https://backpack.tf/profiles/76561198261483133#!/compare/1702598400/1702684800

https://backpack.tf/profiles/76561199210166320#!/compare/1702512000/1702944000

https://backpack.tf/item/10089978416

= 5 keys

Sale 2:

Sold to a bot for 4 keys + 29.77 ref (~0.45 keys)

https://backpack.tf/profiles/76561198216025421#!/compare/1705190400/1705276800

https://backpack.tf/profiles/76561199119132244#!/compare/1705276800/1705363200

https://backpack.tf/item/6864037935

https://gladiator.tf/sales?item=Holy%20Grail%20Taunt:%20Soldier%27s%20Requiem&at=2024-01-16T15:14:39.185Z - gladiator confirms

= 4.45 keys

Other Sales:

#1

https://backpack.tf/profiles/76561199026390261#!/compare/1703376000/1703462400

https://backpack.tf/profiles/76561198216241727#!/compare/1703376000/1703462400

https://backpack.tf/item/13787364172

Untraceable

#2

https://backpack.tf/profiles/76561199139034449#!/compare/1703980800/1704153600

https://backpack.tf/profiles/76561198138242189#!/compare/1703980800/1704240000

https://gladiator.tf/sales?item=Holy%20Grail%20Taunt:%20Soldier%27s%20Requiem&at=2024-01-02T15:14:39.185Z - labelled as 5 keys

https://backpack.tf/item/6527107882

6 keys? was listed for 5.

#3

https://backpack.tf/profiles/76561199210166320#!/compare/1702512000/1702944000

https://backpack.tf/profiles/76561198303306621#!/compare/1702512000/1702771200

https://backpack.tf/item/4256189585

https://backpack.tf/item/6921757872 - marketplace

https://backpack.tf/item/6286639455 - mannco

Unconfirmed Gladiator Sales:

https://gladiator.tf/sales?item=Holy%20Grail%20Taunt:%20Soldier%27s%20Requiem&at=2024-01-07T15:22:54.312Z - January 7th

3 keys + 43.33 ref (~0.7 keys)

https://gladiator.tf/sales?item=Holy%20Grail%20Taunt:%20Soldier%27s%20Requiem&at=2024-01-05T15:22:54.312Z - January 5th

3 keys + 43.11 ref (~0.7 keys)

Sellers:

https://imgur.com/a/b3Tdyvr

https://backpack.tf/item/6527107882 - ~4.45 keys

https://backpack.tf/item/6286639455 - ~4.45 keys

https://backpack.tf/item/6864037935 - ~4.65 keys

https://backpack.tf/item/10089978416 - ~4.85 keys

Sales at:

4.45

5

+ a sale that's either 5 or 6 keys (#2).

On top of all 4 sellers being lower than the sale(s) at 5 keys, the buyer for the 5 key sale is re-selling for less, and the buyer of sale #2 re-sold to a bot for less. I'm happy to exclude 5.

Couldn't find histories for either of the ~3.7 key gladiator sales. If one of them end up being traceable, I will re-suggest and include it in the range.

Taking 4.45 flat.