Item 1

https://backpack.tf/item/13327481445

Sale 1

https://backpack.tf/profiles/76561199118200231#!/compare/1754784000/1754870400

https://backpack.tf/profiles/76561199536459741#!/compare/1754784000/1754870400

No clue

Sale 2

https://backpack.tf/profiles/76561199536459741#!/compare/1755043200/1755129600

https://backpack.tf/profiles/76561199581722058#!/compare/1755043200/1755129600

No clue

Sale 3

https://backpack.tf/profiles/76561199581722058#!/compare/1757462400/1757548800

https://backpack.tf/profiles/76561198127338245#!/compare/1757289600/1757548800

Only a key traces? Incomplete

Item 2

https://backpack.tf/item/13356596144

Listed on mp.tf

Item 3

https://backpack.tf/item/13282857772

Sale 4

https://backpack.tf/profiles/76561198070022327#!/compare/1754092800/1754352000

https://backpack.tf/profiles/76561199085308746#!/compare/1754265600/1754352000

Dumped for 6 keys, 39 ref = ~6.5 keys

Item 4

https://backpack.tf/item/13270377558

Sale 5

https://backpack.tf/profiles/76561198088636158#!/compare/1754265600/1754352000

https://backpack.tf/profiles/76561198063640894#!/compare/1754179200/1754265600

Bulk inv buy

Sale 6

https://backpack.tf/profiles/76561198063640894#!/compare/1754265600/1754352000

https://backpack.tf/profiles/76561198053697018#!/compare/1756166400/1756684800

No clue

Sale 7

https://backpack.tf/profiles/76561198053697018#!/compare/1756944000/1757030400

https://backpack.tf/profiles/76561199059160806#!/compare/1756944000/1757030400

Keys instantly used, dumped for an unknown amount

Item 5

https://backpack.tf/item/13248341508

Sale 8

https://backpack.tf/profiles/76561199446578917#!/compare/1757376000/1757462400

https://backpack.tf/profiles/76561199017959799#!/compare/1757289600/1757462400

Probably gambling

Item 6

https://backpack.tf/item/13242148987

Sale 9

https://backpack.tf/profiles/76561199026390261#!/compare/1754438400/1754524800

https://backpack.tf/profiles/76561199017959799#!/compare/1754438400/1754524800

No clue

Sale 10

https://backpack.tf/profiles/76561199017959799#!/compare/1754524800/1754611200

https://backpack.tf/profiles/76561198983856237#!/compare/1754524800/1754611200

Probably gambling

Sale 11

https://backpack.tf/profiles/76561198983856237#!/compare/1754697600/1754784000

https://backpack.tf/profiles/76561199046064612#!/compare/1754524800/1754697600

Probably gambling

Mp.tf

https://marketplace.tf/items/tf2/31348;5;u3123

https://backpack.tf/item/13513897605

$14.27 / $1.81 = ~8 keys (Sep 1)

$14.27 / $1.80 = ~8 keys (Sep 4)

Total Sales

6.5, 8, 8

https://imgur.com/a/Z9keb4D

Sellers @ ~7

I'll use the buyer dump as a low end and go with 6.5 - 8 keys to accommodate the lower sellers c:

Unsolds:

https://backpack.tf/item/13239207645 - 7

https://backpack.tf/item/13242148987 - 7

https://backpack.tf/item/13282857772 - ~7.2

https://backpack.tf/item/13356596144 - $14.27

https://backpack.tf/item/13239514775 - ~9.6

https://backpack.tf/item/13241972884 - ~9.6