Sale 1:

https://backpack.tf/profiles/76561198986747837#!/compare/1589846400/1589932800

https://backpack.tf/profiles/76561198072374854#!/compare/1588723200/1589846400

https://backpack.tf/profiles/76561198986747837#!/compare/1589587200/1589846400

https://backpack.tf/profiles/76561198273988414#!/compare/1589760000/1589846400

https://backpack.tf/profiles/76561198212086448#!/compare/1589846400/1589932800

https://backpack.tf/profiles/76561198273988414#!/compare/1589846400/1589932800

https://backpack.tf/profiles/76561198108020681#!/compare/1589846400/1589932800

https://backpack.tf/profiles/76561198305494036#!/compare/1589932800/1590019200

untrace / Bulk / gambling?

sale 2:

https://backpack.tf/profiles/76561198305494036#!/compare/1589932800/1590019200

https://backpack.tf/profiles/76561198069493147#!/compare/1589932800/1590019200

Sold for 9 keys(?)

sale 3:

https://backpack.tf/profiles/76561198069493147#!/compare/1590019200/1590364800

https://backpack.tf/profiles/76561198447536098#!/compare/1590192000/1590278400

Sold for N&B Specs + ~1.49 key in sweets

use there, few sales.

sale 4:

https://backpack.tf/profiles/76561198447536098#!/compare/1591315200/1591401600

https://backpack.tf/profiles/76561198851895221#!/compare/1591315200/1591401600

Sold for 13 keys

sale 5:

https://backpack.tf/profiles/76561198851895221#!/compare/1591401600/1591574400

https://backpack.tf/profiles/76561198386346780#!/compare/1591401600/1591488000

Sold for 13 keys

sale 6:

https://backpack.tf/profiles/76561198386346780#!/compare/1591401600/1591488000

https://backpack.tf/profiles/76561198203564124#!/compare/1591401600/1591488000

Sold with 5 keys for C9 Gilded

use there

sale 7:

https://backpack.tf/profiles/76561198183849619#!/compare/1588809600/1589328000

https://backpack.tf/profiles/76561198114635132#!/compare/1589068800/1589155200

Sold for 10 keys

sale 8:

https://backpack.tf/profiles/76561198026526425#!/compare/1589760000/1589846400

https://backpack.tf/profiles/76561198038076640#!/compare/1589241600/1590105600

Untrace

sale 9:

https://backpack.tf/profiles/76561198038076640#!/compare/1589241600/1590105600

https://backpack.tf/profiles/76561198890484759#!/compare/1590019200/1590192000

https://backpack.tf/profiles/76561198026526425#!/compare/1590364800/1590537600

Untrace

sale 10:

https://backpack.tf/profiles/76561198026526425#!/compare/1590537600/1590624000

https://backpack.tf/profiles/76561198305494036#!/compare/1590537600/1590624000

QS

sale 11:

https://backpack.tf/profiles/76561198305494036#!/compare/1590537600/1590624000

https://backpack.tf/profiles/76561198386195044#!/compare/1590537600/1590624000

Sold for 11 keys

Sale 12:

https://backpack.tf/profiles/76561198121675983#!/compare/1591142400/1591228800

https://backpack.tf/profiles/76561198061489334#!/compare/1591142400/1591228800

Bulk

sale 13:

https://marketplace.tf/items/tf2/30006;5;u6

$28.99 / $1.88 = 15.42 keys

Total sales @:

9, 10, 11, 13, 13, 15 keys

buyers at ~11 keys,

given sales below 11, and more buyers at ~8,

taking 11 - 13 keys.