Resuggestion, thanks to Foamy for the info!

Sale 1:

https://backpack.tf/profiles/76561198307761034#!/compare/1562716800/1562803200

https://backpack.tf/profiles/76561198096251037#!/compare/1562284800/1562803200

Sold with sweets for 0.61 keys in sweets + C9 Mann o War

use there

Sale 2:

https://backpack.tf/profiles/76561198096251037#!/compare/1564531200/1565136000

https://backpack.tf/profiles/76561198072328749#!/compare/1565049600/1565136000

Sold for HoS Vampire

use there

Sale 3:

https://backpack.tf/profiles/76561198080179568#!/compare/1562198400/1562284800

https://backpack.tf/profiles/76561198216806363#!/compare/1562198400/1562284800

Sold for 14 keys

Sale 4:

https://backpack.tf/profiles/76561198341171690#!/compare/1563753600/1563840000

https://backpack.tf/profiles/76561198062993488#!/compare/1563753600/1567468800

Sold for 14 keys

Sale 5:

https://backpack.tf/profiles/76561198862126261#!/compare/1564099200/1564272000

https://backpack.tf/profiles/76561198331167728#!/compare/1564099200/1564185600

https://backpack.tf/profiles/76561198862126261#!/compare/1564272000/1564358400

Tradeback

Sale 6:

https://backpack.tf/profiles/76561198862126261#!/compare/1566000000/1566086400

https://backpack.tf/profiles/76561198047941585#!/compare/1566086400/1566172800

https://backpack.tf/profiles/76561198862126261#!/compare/1566086400/1566172800

tradeback....?

Sale 7:

https://backpack.tf/profiles/76561198862126261#!/compare/1567036800/1567382400

https://backpack.tf/profiles/76561198156037120#!/compare/1567468800/1567555200

SCM

Sale 8:

https://backpack.tf/profiles/76561198109900692#!/compare/1567987200/1568073600

https://backpack.tf/profiles/76561198296192034#!/compare/1568073600/1568160000

Sold for 13 keys

Sale 9:

https://backpack.tf/profiles/76561198840397915#!/compare/1561248000/1561334400

https://backpack.tf/profiles/76561198058044110#!/compare/1561334400/1561420800

Untrace

Sale 10:

https://backpack.tf/profiles/76561198870660687#!/compare/1566000000/1566086400

https://backpack.tf/profiles/76561198335791307#!/compare/1565913600/1566000000

Untrace

Sale 11:

https://backpack.tf/profiles/76561198274447983#!/compare/1562630400/1562889600

https://backpack.tf/profiles/76561198272154789#!/compare/1562716800/1562803200

Sold for ~12 keys

Sale 12:

https://backpack.tf/profiles/76561198272154789#!/compare/1563494400/1563667200

https://backpack.tf/profiles/76561198051253246#!/compare/1563580800/1563667200

Sold for 13 keys

Sale 13:

https://backpack.tf/profiles/76561198051253246#!/compare/1563667200/1563753600

https://backpack.tf/profiles/76561198038076640#!/compare/1563580800/1563753600

https://backpack.tf/profiles/76561198306787854#!/compare/1563494400/1563753600

Bulk / untrace

sale 14:

https://backpack.tf/profiles/76561198306787854#!/compare/1563753600/1563840000

https://backpack.tf/profiles/76561198091342225#!/compare/1563667200/1563840000

https://backpack.tf/profiles/76561198827759757#!/compare/1563753600/1563840000

https://backpack.tf/profiles/76561198121112164#!/compare/1563753600/1563840000

Untrace / bulk

Sale 15:

https://backpack.tf/profiles/76561198121112164#!/compare/1564272000/1564444800

https://backpack.tf/profiles/76561198100248168#!/compare/1564358400/1564444800

Untrace

Sale 16:

https://backpack.tf/profiles/76561198100248168#!/compare/1564444800/1564531200

https://backpack.tf/profiles/76561198134546405#!/compare/1564444800/1564531200

https://backpack.tf/profiles/76561198963003558#!/compare/1566259200/1566691200

Untrace

Sale 17:

https://backpack.tf/profiles/76561198963003558#!/compare/1566691200/1567123200

https://backpack.tf/profiles/76561198341171690#!/compare/1566950400/1567036800

QS / Untrace

Sale 18:

https://backpack.tf/profiles/76561198341171690#!/compare/1567296000/1567382400

https://backpack.tf/profiles/76561198311704368#!/compare/1567209600/1567382400

Sold for 16 keys

Sale 19:

https://backpack.tf/profiles/76561198369906747#!/compare/1560384000/1560470400

https://backpack.tf/profiles/76561198363395191#!/compare/1560470400/1560556800

QS

Sale 20:

https://backpack.tf/profiles/76561198363395191#!/compare/1560988800/1561075200

https://backpack.tf/profiles/76561198098054379#!/compare/1560988800/1561075200

Sold for keys, can trace 9, probably more.

Sale 21:

https://marketplace.tf/items/tf2/31025;5;u11

$33 / $1.82 = 18.13 keys

Total sales @:

12, 13, 13, 14, 14, 16, 18.13 keys

New sales:

Sale 22:

https://backpack.tf/profiles/76561198360414915#!/compare/1572566400/1572652800

https://backpack.tf/profiles/76561198437849017#!/compare/1572393600/1572566400

https://backpack.tf/profiles/76561198437849017#!/compare/1572566400/1572652800

Untrace

sale 23:

https://backpack.tf/profiles/76561198437849017#!/compare/1572652800/1572739200

https://backpack.tf/profiles/76561198046813997#!/compare/1572652800/1572739200

Sold for C9 Beret

Sale 24:

https://backpack.tf/profiles/76561198046813997#!/compare/1573171200/1573257600

https://backpack.tf/profiles/76561198348676293#!/compare/1572912000/1573344000

Sold for ~13 keys

Sale 25:

https://backpack.tf/profiles/76561198348676293#!/compare/1573344000/1573862400

https://backpack.tf/profiles/76561198410242972#!/compare/1573257600/1573344000

Untrace

Sale 26:

https://backpack.tf/profiles/76561198410242972#!/compare/1573516800/1573689600

https://backpack.tf/profiles/76561198306076386#!/compare/1573603200/1573689600

Sold for C9 Bottle(17.5)

https://bot.tf/stats/listings/M17ERDD0

B/O of 15 keys, capping

Sale 27:

https://backpack.tf/profiles/76561198306076386#!/compare/1573603200/1573689600

https://backpack.tf/profiles/76561198384323777#!/compare/1573603200/1573689600

Bulky

Sale 28:

https://backpack.tf/profiles/76561198174890191#!/compare/1568937600/1569024000

https://backpack.tf/profiles/76561198972294135#!/compare/1568937600/1569024000

Sold for ~9 keys(?)

sale 29:

https://backpack.tf/profiles/76561198972294135#!/compare/1568937600/1569024000

https://backpack.tf/profiles/76561198125389744#!/compare/1568937600/1569024000

Bulk

sale 30:

https://backpack.tf/profiles/76561198968253262#!/compare/1573171200/1573257600

https://backpack.tf/profiles/76561198140719727#!/compare/1573171200/1573257600

Sold for Aussie Amby(~8.5)

Sale 31:

https://backpack.tf/profiles/76561198140719727#!/compare/1573257600/1573344000

https://backpack.tf/profiles/76561198357046243#!/compare/1573171200/1573257600

Untrace

sale 32:

https://backpack.tf/profiles/76561198296192034#!/compare/1571356800/1571443200

https://backpack.tf/profiles/76561198024805594#!/compare/1571356800/1571443200

Sold for 8 keys

Sale 33:

https://backpack.tf/profiles/76561198024805594#!/compare/1571356800/1571443200

https://backpack.tf/profiles/76561198215116737#!/compare/1571356800/1571443200

Sold for 12 keys

sale 34:

https://backpack.tf/profiles/76561198215116737#!/compare/1571356800/1571443200

https://backpack.tf/profiles/76561198341171690#!/compare/1571356800/1571443200

QS

sale 35:

https://backpack.tf/profiles/76561198098054379#!/compare/1571788800/1572220800

https://backpack.tf/profiles/76561198357093059#!/compare/1571788800/1571875200

https://backpack.tf/profiles/76561198198878335#!/compare/1570838400/1571875200

Untrace then bulky

sale 36:

https://backpack.tf/profiles/76561198333986358#!/compare/1573689600/1573776000

https://backpack.tf/profiles/76561198340611709#!/compare/1573689600/1573776000

Sold for 15 keys

Sale 37:

https://marketplace.tf/items/tf2/31025;5;u11

$35 / $1.80 = 19.44 keys

Total after new sales:

8, 8.5, 12, 12, 13, 13, 13, 14, 14, 15, 15, 16, 18 keys

Foamy's Part:

Looking at the current market Id probably cut 18 from the range.

Taking 12 - 16 keys