Sale 1:

https://backpack.tf/profiles/76561197964171516#!/compare/1531008000/1531094400

Untrace.

Sale 2:

https://backpack.tf/profiles/76561198066571888#!/compare/1529712000/1529798400

https://backpack.tf/profiles/76561198123163113#!/compare/1529712000/1532995200

SCM, untrace.

Sale 3:

https://backpack.tf/profiles/76561198337734785#!/compare/1531094400/1531180800

https://backpack.tf/profiles/76561198275390406#!/compare/1530662400/1531267200

Untrace.

Sale 4:

https://backpack.tf/profiles/76561198069493147#!/compare/1532563200/1532649600

https://backpack.tf/profiles/76561198143610563#!/compare/1532563200/1532649600

Sold for Bubbling Tyrant Helm

Helm Mini:

https://backpack.tf/suggestion/5b7ec080cf6c756865713675

Suggestion for 13.5 keys

Sale 5:

https://backpack.tf/profiles/76561198143610563#!/compare/1532649600/1532736000

https://backpack.tf/profiles/76561198125905016#!/compare/1532476800/1532736000

Sold for TW Airdog

Use there.

Sale 6:

https://backpack.tf/profiles/76561198435061144#!/compare/1530835200/1531008000

Untrace.

Sale 7:

https://backpack.tf/profiles/76561198435061144#!/compare/1531008000/1531180800

https://backpack.tf/profiles/76561198081491001#!/compare/1530835200/1531094400

Untrace.

Sale 8:

https://backpack.tf/profiles/76561198081491001#!/compare/1531440000/1531526400

https://backpack.tf/profiles/76561198107192699#!/compare/1531440000/1531526400

Bulk.

Sale 9:

https://backpack.tf/profiles/76561198107192699#!/compare/1531612800/1531699200

https://backpack.tf/profiles/76561198061108191#!/compare/1531612800/1531699200

Untrace.

Sale 10:

https://backpack.tf/profiles/76561198037137394#!/compare/1529625600/1530057600

https://backpack.tf/profiles/76561197980830714#!/compare/1529884800/1530057600

Sold for 11 keys

Sale 11:

https://backpack.tf/profiles/76561197980830714#!/compare/1530662400/1530748800

Bulk.

Sale 12:

https://backpack.tf/profiles/76561198067397074#!/compare/1531180800/1531353600

https://backpack.tf/profiles/76561198128880549#!/compare/1530230400/1531353600

Sold for 12 keys

Sale 13:

https://backpack.tf/profiles/76561198128880549#!/compare/1531958400/1532044800

https://backpack.tf/profiles/76561198115699456#!/compare/1531958400/1532044800

Sold with ~1 key in sweets for Pro KS Aussie FaN(~10)

Total is 9 keys

Sale 14:

https://backpack.tf/profiles/76561198115699456#!/compare/1532390400/1532476800

https://backpack.tf/profiles/76561198128578694#!/compare/1532131200/1532476800

Sold for 12 keys + ~1 key in sweets

Total is 13 keys

Sale 15:

https://backpack.tf/profiles/76561198128578694#!/compare/1532476800/1532563200

https://backpack.tf/profiles/76561198053728930#!/compare/1532476800/1533168000

Sold with 2 keys for Subatomic Translator(18)

Total is 16 keys

Sale 16:

https://backpack.tf/profiles/76561198848430616#!/compare/1533168000/1533254400

Sold with 6 keys for Stormy Company Mann

Mann Mini:

https://backpack.tf/suggestion/5b7ebabdcf6c75686d0a9ab0

Suggestion for 19.5 keys

Total is 13.5 keys.

Sale 17:

https://backpack.tf/profiles/76561198053728930#!/compare/1533254400/1533859200

Untrace.

Sale 18:

https://backpack.tf/profiles/76561198086197768#!/compare/1533513600/1533600000

https://backpack.tf/profiles/76561198092449612#!/compare/1533427200/1533513600

Untrace.

Sale 19:

https://backpack.tf/profiles/76561198195790934#!/compare/1533600000/1533945600

Untrace.

Sale 20:

https://backpack.tf/profiles/76561198111322090#!/compare/1533600000/1533686400

Untrace.

Sale 21:

https://backpack.tf/profiles/76561198111322090#!/compare/1533772800/1533859200

https://backpack.tf/profiles/76561197961703349#!/compare/1533772800/1533859200

Untrace.

Sale 22:

https://backpack.tf/profiles/76561197961703349#!/compare/1533859200/1534118400

https://backpack.tf/profiles/76561198132577068#!/compare/1533945600/1534118400

Untrace

Sale 23, 24:

https://marketplace.tf/items/30984;5;u58

Sold for 29.99, 29.99 USD

Keys at 1.99, 1.98

Totals are 15.07, 15.15 keys

Total Sales @:

9, 11, 12, 13, 13.5, 13.5, 15.07, 15.15, 16 keys

Unsold for month + at 13 keys

https://backpack.tf/item/6812979811

https://backpack.tf/item/6760782345

https://i.imgur.com/4jfmuy0.jpg

Buyers up to 7 keys

Let's go with 9 - 13 keys.