Marketplace.tf sales:

https://marketplace.tf/items/tf2/478;5;u34

Sale #1: $16.00 / $1.85 (https://manic.tf/keyprice/?at=2020-08-07) = 8.65 ~ 8.5 keys

Item 1: https://backpack.tf/item/1712030666 - Only marketplace.tf withdrawal

Sale #2: $11.15 / $1.85 (https://manic.tf/keyprice/?at=2020-08-28) =6.03 ~ 6 keys

Item 2: https://backpack.tf/item/1124657264 - Only marketplace.tf withdrawal

Sale #3: $14.00 / $1.83 (https://manic.tf/keyprice/?at=2020-09-04) = 7.65 ~ 7.5 keys

unknown item history

All unknown B/O.

Item tracing:

Item 3: https://backpack.tf/item/509118754 (hidden)

Sale #4

traced only 1 key/missing

https://backpack.tf/profiles/76561198337734785#!/compare/1597536000/1597622400

https://backpack.tf/profiles/76561198280524116#!/compare/1597536000/1597622400

Sale #5

total missing/just transfer from Pyro bot to SugarCookies! :D to sell it on marketplace.tf

https://backpack.tf/profiles/76561198280524116#!/compare/1597536000/1597622400

https://backpack.tf/profiles/76561198029074524#!/compare/1597536000/1597622400

Item 4: https://backpack.tf/item/1372856395 (hidden)

Skipping trade from scammer alt

Sale #6

traced 7 keys

https://backpack.tf/profiles/76561198311498888#!/compare/1597622400/1597708800 (ID: 9125729805)

https://backpack.tf/profiles/76561198296433256#!/compare/1596931200/1597708800

Scrap.TF

https://backpack.tf/profiles/76561198296433256#!/compare/1597708800/1598313600

https://backpack.tf/profiles/76561198135388328#!/compare/1597622400/1598313600 (missing)

Scrap.TF

https://backpack.tf/profiles/76561198135388328#!/compare/1598140800/1598227200 (missing)

https://backpack.tf/profiles/76561198147143722#!/compare/1598140800/1598400000 (traced 6 keys here)

--------------------------------------------

Current listings: https://gyazo.com/973299fe474ef82cc7574fb8741fc4e6

unsold for 7 and 8 keys, listed since 17 days ago

buying at highest 6.11 keys

2 seller on marketplace.tf:

1 @ $14.00 / ~$1.83 = 7.65

1 @ $14.50 / ~$1.83 = 7.92

--------------------------------------------

Valid sales: 8.5, 6, 7.5, 7

I think it's safe to exclude 7.5 and 8.5 keys since 7 and 8 keys has been unsold for 3 weeks (or maybe longer).

oh wait..

Both current seller (same person):

https://backpack.tf/item/1347795364 - been there since 2019-07-17

https://backpack.tf/item/1642343191 - been there since 2018-08-12

Hurmmmm.......

Taking 6 - 7 keys