Sale 1:

Sold for 8 keys

https://backpack.tf/profiles/76561198151236221#!/compare/1703721600/1703894400

https://backpack.tf/profiles/76561198106511423#!/compare/1703548800/1703721600

https://backpack.tf/item/3399402574

Keys on the buyer's end. One key and the metal weren't involved.

= 8 keys

Sale 2:

Sold for 7 keys

https://backpack.tf/profiles/76561199062879180#!/compare/1699228800/1699574400

https://backpack.tf/profiles/76561198083609920#!/compare/1698969600/1699660800

https://backpack.tf/item/2846387777

= 7 keys

Sale 3:

Sold with half a key in metal for 7 keys

https://backpack.tf/profiles/76561199059632349#!/compare/1703635200/1703721600

https://backpack.tf/profiles/76561198151236221#!/compare/1703548800/1703721600

https://backpack.tf/item/3399402574

= 6.5 keys

Sale 4:

Sold for 5 keys + Bruiser's Bandana (~11 ref) + 6.88 ref (rounds to 5.5 keys

https://backpack.tf/profiles/76561199026390261#!/compare/1703203200/1703289600

https://backpack.tf/profiles/76561198099685235#!/compare/1703203200/1703289600

https://backpack.tf/item/3619225761

= 5.5 keys

Sale 5:

Sold for 5 keys + 20 ref

https://backpack.tf/profiles/76561198094133017#!/compare/1702684800/1702771200

https://backpack.tf/profiles/76561198279703584#!/compare/1702512000/1702684800

https://backpack.tf/item/3399402574

= 5.5 keys

Sale 6:

Sold for 5 keys

https://backpack.tf/profiles/76561198453530349#!/compare/1702771200/1702857600

https://backpack.tf/profiles/76561198077625769#!/compare/1702857600/1702944000

https://backpack.tf/item/13041520141

In case of any doubt, here is their listing:

https://next.backpack.tf/classifieds/snapshots/Holy%20Grail%20Taunt:%20Fresh%20Brewed%20Victory/657e884038793a30ae0c2892

https://imgur.com/a/cGYUYJQ - ~5 keys

= 5 keys

Other Sales:

#1

https://backpack.tf/profiles/76561198453530349#!/compare/1702339200/1702425600

https://backpack.tf/profiles/76561198215813163#!/compare/1702339200/1702425600

https://backpack.tf/item/13611119743

Untraceable

#2

https://backpack.tf/profiles/76561199436613904#!/compare/1702512000/1702598400

https://backpack.tf/profiles/76561198453530349#!/compare/1702512000/1702598400

https://backpack.tf/item/13041520141

Untraceable

#3

https://backpack.tf/profiles/76561198983856237#!/compare/1703808000/1703894400

https://backpack.tf/profiles/76561199564942025#!/compare/1703721600/1703808000

https://backpack.tf/item/12610175733

Untraceable. Gambled prior.

#4

https://backpack.tf/profiles/76561198014060803#!/compare/1701129600/1701388800

https://backpack.tf/profiles/76561198135388328#!/compare/1701043200/1701129600

https://backpack.tf/item/5307694183

Bulk to scrap

#5

https://backpack.tf/profiles/76561198135388328#!/compare/1701388800/1701475200

https://backpack.tf/profiles/76561198096025644#!/compare/1650499200/1702166400

https://backpack.tf/item/5307694183

Untraceable. 4 keys match, more would've been involved.

#6

https://backpack.tf/profiles/76561198178445551#!/compare/1702166400/1702598400 - Near ID: 13918345063

https://backpack.tf/profiles/76561199026390261#!/compare/1702512000/1702598400

https://backpack.tf/item/3619225761

Untraceable. 1 key and 1 rec match

#7

https://backpack.tf/profiles/76561198279703584#!/compare/1703376000/1703980800

https://backpack.tf/profiles/76561199111073161#!/compare/1703376000/1703462400

https://backpack.tf/item/3399402574

Untraceable, probably a cashout

https://backpack.tf/item/5701881871 - unusualified

https://backpack.tf/item/3680153221 - mannco

Marketplace Sales:

https://marketplace.tf/items/tf2/1113;5;u3003

$17.99, November 12th

https://marketplace.tf/items/tf2/5021;6

Keys were $1.73.

17.99/1.73 = ~10.39, rounds to 10 (or 10.5)

Sellers:

https://imgur.com/a/f1s9V9q

https://backpack.tf/item/12827956066 - 20 keys

Sales at:

5

5.5 (2x)

6.5

7

8

10 (marketplace)

The marketplace sale looks like an outlier. I'd include it if it were a pure sale, which has more weighting, but it's not. Excluding 10.

Taking 5-8.